Gen V Stock Belanger Arrow Stage 1

[Bryan Savage]

So here's the uncut graph. Three sets of runs all overlaid. Same dyno, same car.

2018-09-04 All Together.jpg

Stock Car Peak Numbers:
542.23 hp, 500.57 ft-lb
549.30 hp, 501.64 ft-lb
553.67 hp, 504.19 ft-lb

The temperature in the shop was +92°F. IATs not monitored.

Belanger Headers & Mufflers, with high-flow cats, no check engine light Peak Numbers:
555.73 hp, 509.51 ft-lb
535.49 hp, 505.84 ft-lb
541.20 hp, 504.90 ft-lb
556.05 hp, 516.46 ft-lb

The temperature in the shop was +73°F. Again, IATs not monitored.

Belanger Exhaust and Arrow Controller (canned tune) Peak Numbers:
560.70 hp, 512.51 ft-lb
548.85 hp, 515.59 ft-lb
543.84 hp, 508.98 ft-lb

The temperature in the shop was +90°F. No IATs.

SO,

I see no statistical significance in any of these numbers to definitively claim there was a power gain. The top run from each session was only separated by 7.03 hp, and when back to back runs in the same session differed by as much as twenty horsepower, I can't see a reliably-measurable difference.

2018-09-04 Best Of Each.jpg

The red line in the above graph is the Arrow line. There's a massive apparent loss of power between 4,200 rpm and 5,000 rpm, and the peak power only happens north of 6,000 rpm. You can't see this in the "all in one" graph, since it's lost in the noise.

Where am I going with this?

Nowhere.

I like the sound of the Belangers and I really like the pop of the Arrow. The sills are only warm to the touch, the skip shift is gone, and the car feels smoother to drive and shift at all speeds. Even the Dyno tech asked what I'd done to it since it sounded so different when he fired it up. I don't think any of these mods are a waste of money and not worth doing. My biggest takeaway from this, since I'm relatively new to dynoing things, is that if you can't measure the same thing twice in a row and get the same answer, you just can't verify any claim of power gains. There's just too much experimental error here. You'd need an engine dyno in a climate-controlled lab to knock out some of the uncertainty.

To those of you who have dynoed your cars and reported numbers, have you only taken the best run? Do you see as much variance as I did during multiple runs? Do you have this big dip in power, consistently, around 4,700 rpm?

[dewilmoth]

This is fantastic information and I appreciate the objectiveness.

[J TNT]

Good info Bryan , interesting the difference between stock and Balenger ............

[Voice of Reason]

This is bizarre. You are showing essentially no difference at all and my dyno from 3.5 years ago shows I gained a nice amount under the curve, not to mention my peak noticeably increased. I could easily feel the difference too. Your results showing it's doing nothing make me wonder if you have another issue going on. Have you ever changed your plugs or wires?

[cubeman]

This is bizarre. You are showing essentially no difference at all and my dyno from 3.5 years ago shows I gained a nice amount under the curve, not to mention my peak noticeably increased. I could easily feel the difference too. Your results showing it's doing nothing make me wonder if you have another issue going on. Have you ever changed your plugs or wires?

Dyno's vary. You could dyno at two different dyno's (Assuming both the same brand) and could get a 20hp variance like above did. What it does show is that just bolting on parts on this car doesn't make any additional power. The stock PCM is just going to run as usual. The fact he gained nothing off the Arrow PCM makes me wonder what's going on as I thought the Arrow PCM does advance timing and add fuel.


My car is going under the knife soon enough and we'll be doing a pull with a tune by Torrie (HPTuners) with ARH Headers, Cat(less), Exhaust, Pulley. We'll be using a dynojet so I'll have some numbers to compare with other dynojet numbers.

[Bryan Savage]

This is bizarre. You are showing essentially no difference at all and my dyno from 3.5 years ago shows I gained a nice amount under the curve, not to mention my peak noticeably increased. I could easily feel the difference too. Your results showing it's doing nothing make me wonder if you have another issue going on. Have you ever changed your plugs or wires?

Yeah, I was on the phone with Lou Belanger a few times. Long story short, I put the left front O2 sensor wires under tension when I installed the system and over 1,600 miles, three wires pulled out and gave me a MIL. All my fault. Anyway, he was thinking spark plugs should be changed way more often than I had (read: never), so I put a new set of OE RE10PMC5 plugs in at 37,600 miles. This is what they looked like:
2018-04-21 Spark Plugs.jpg
All the gaps were fine. These plugs are fine. I put new plug wires on too. This was all after the first dyno run.

Dyno's vary. You could dyno at two different dyno's (Assuming both the same brand) and could get a 20hp variance like above did. What it does show is that just bolting on parts on this car doesn't make any additional power. The stock PCM is just going to run as usual. The fact he gained nothing off the Arrow PCM makes me wonder what's going on as I thought the Arrow PCM does advance timing and add fuel.


My car is going under the knife soon enough and we'll be doing a pull with a tune by Torrie (HPTuners) with ARH Headers, Cat(less), Exhaust, Pulley. We'll be using a dynojet so I'll have some numbers to compare with other dynojet numbers.

Correct. The stock ECU is going to keep doing what it's told to do. And the Arrow controller is tuned for driveability; not for peak power. It's not like SRT detuned things.

A custom tune in a controlled environment would produce better results. For straight-up bolt-ons, I don't think you'll see anything you can prove.

[Steve M]

A custom tune in a controlled environment would produce better results. For straight-up bolt-ons, I don't think you'll see anything you can prove.

On the dyno, or on the street? The gains from those mods shouldn't be in the noise unless you have something else going on with your build...a full bolt-on Viper should be substantially faster than a stock one, like in this clip:



I'd take a good hard look at your Belanger "high flow" cats. Any guess as to how he got them to not throw a CEL with the stock PCM? I have one...

[outnumbered]

Brian,
Great write up. My graph is below; albeit a little different. We did make multiple pulls with each but unfortunately I don’t have those on my graph sheet. However I do believe we took the best of each.

1. Stock with full Belanger
2. Arrow with full Belanger
3. Torrie tuned with full Belanger ( this was the last pull and hottest time of the day )

Interesting that our Arrow pulls are almost identical.

[stradman]

Brian,
Great write up. My graph is below; albeit a little different. We did make multiple pulls with each but unfortunately I don’t have those on my graph sheet. However I do believe we took the best of each.

1. Stock with full Belanger
2. Arrow with full Belanger
3. Torrie tuned with full Belanger ( this was the last pull and hottest time of the day )

Interesting that our Arrow pulls are almost identical.

Bear in mind your figures are STD which are about 2% higher than SAE. So 540 on your OEM and 559 on your Arrows would be about 529 and 548 respectively using SAE.

[Scot@Prefix]

So here's the uncut graph. Three sets of runs all overlaid. Same dyno, same car.

2018-09-04 All Together.jpg

Stock Car Peak Numbers:
542.23 hp, 500.57 ft-lb
549.30 hp, 501.64 ft-lb
553.67 hp, 504.19 ft-lb

The temperature in the shop was +92°F. IATs not monitored.

Belanger Headers & Mufflers, with high-flow cats, no check engine light Peak Numbers:
555.73 hp, 509.51 ft-lb
535.49 hp, 505.84 ft-lb
541.20 hp, 504.90 ft-lb
556.05 hp, 516.46 ft-lb

The temperature in the shop was +73°F. Again, IATs not monitored.

Belanger Exhaust and Arrow Controller (canned tune) Peak Numbers:
560.70 hp, 512.51 ft-lb
548.85 hp, 515.59 ft-lb
543.84 hp, 508.98 ft-lb

The temperature in the shop was +90°F. No IATs.

SO,

I see no statistical significance in any of these numbers to definitively claim there was a power gain. The top run from each session was only separated by 7.03 hp, and when back to back runs in the same session differed by as much as twenty horsepower, I can't see a reliably-measurable difference.

2018-09-04 Best Of Each.jpg

The red line in the above graph is the Arrow line. There's a massive apparent loss of power between 4,200 rpm and 5,000 rpm, and the peak power only happens north of 6,000 rpm. You can't see this in the "all in one" graph, since it's lost in the noise.

Where am I going with this?

Nowhere.

I like the sound of the Belangers and I really like the pop of the Arrow. The sills are only warm to the touch, the skip shift is gone, and the car feels smoother to drive and shift at all speeds. Even the Dyno tech asked what I'd done to it since it sounded so different when he fired it up. I don't think any of these mods are a waste of money and not worth doing. My biggest takeaway from this, since I'm relatively new to dynoing things, is that if you can't measure the same thing twice in a row and get the same answer, you just can't verify any claim of power gains. There's just too much experimental error here. You'd need an engine dyno in a climate-controlled lab to knock out some of the uncertainty.

To those of you who have dynoed your cars and reported numbers, have you only taken the best run? Do you see as much variance as I did during multiple runs? Do you have this big dip in power, consistently, around 4,700 rpm?

Do you have a pic of the Belanger high flow cats? There seems to be a couple different high flow cats from Belanger, and some of them are stock non high flow.

The Stage 1 controller actually leans the car slightly since the factory program errors on the rich side for safety. The main purpose of the stage 1 controller is so you can do modifications to the car and the computer will allow it, without going into limp.

The thing i see missing from all the information is the AFR charting with the pulls, might add to the story!

[Jack B]

Do you have a pic of the Belanger high flow cats? There seems to be a couple different high flow cats from Belanger, and some of them are stock non high flow.

The Stage 1 controller actually leans the car slightly since the factory program errors on the rich side for safety. The main purpose of the stage 1 controller is so you can do modifications to the car and the computer will allow it, without going into limp.

The thing i see missing from all the information is the AFR charting with the pulls, might add to the story!

Without the AF and the IAT it is hard to compare.

[Scot@Prefix]

Sorry those are not high flow cats
They are dual ceramic core cats manufactured by magnaflow.
Compared to a high flow cat you are leaving 20 rear wheel hp on the table.

[8400cc]

Sorry those are not high flow cats
They are dual ceramic core cats manufactured by magnaflow.
Compared to a high flow cat you are leaving 20 rear wheel hp on the table.

Sounds like that settles that.....

[Bryan Savage]

Sounds like that settles that.....

Deal With It.gif

[Bryan Savage]

If you have the file plot rpm and mph, it looks like you are slipping on the rollers. If you use zero smoothing your trace will get real ugly. I have done four or five sessions and my car has slipped drastically except in the last session which was at Arrow.

That's a good idea. I'd seen the thought of slippage on these forums before. I'll ask the shop if they also log mph and see if they can switch the axes and make me a new graph.

Without the AF and the IAT it is hard to compare.

Looks like I'd better go back to the dyno and log some data! I didn't even think of doing that before, but my OBD Link MX can do that.

2018-09-11 09.22.36.jpg

Sorry those are not high flow cats
They are dual ceramic core cats manufactured by magnaflow.
Compared to a high flow cat you are leaving 20 rear wheel hp on the table.

BALLS!!!!

Although, that explains my lack of MIL....

I did mention to Lou when I was ordering the system that I wanted to attempt to remain emissions-compliant. I guess I just assumed I got high-flow cats due to the decrease in sill temperature. For the life of me, I can't find the paperwork for the order. Good eye for recognizing the cats, Scot!!!

Since those are all welded in, sounds like perhaps a change to the back half of the exhaust system is in order...

[SilveRT8]

Sorry those are not high flow cats
They are dual ceramic core cats manufactured by magnaflow.
Compared to a high flow cat you are leaving 20 rear wheel hp on the table.

Hi Scott,
On my '16 GTC /TA2 group, I also have Belanger Headers with HF Cats necked down to 2 1/2'' to fit the stock mufflers size. Here is a pic of my cat which looks like the magnaflow non HF cat. Can you confirm on this and do you sell the High flow cat also necked down to 2 1/2'' or should I be better off also changing the mufflers to a 3'' inlet size to fit with your version of the cats? I would not like to leave 20 RWHP on the table. !

[Scot@Prefix]

Hi Scott,
On my '16 GTC /TA2 group, I also have Belanger Headers with HF Cats necked down to 2 1/2'' to fit the stock mufflers size. Here is a pic of my cat which looks like the magnaflow non HF cat. Can you confirm on this and do you sell the High flow cat also necked down to 2 1/2'' or should I be better off also changing the mufflers to a 3'' inlet size to fit with your version of the cats? I would not like to leave 20 RWHP on the table. !

Yes that is a standard cat, keep in mind it is probably higher flowing than the stock cat system! Also it may not throw a code so no CEL, easy installation without issues.
True high flow cats will throw a code.

What we do is take a high flow cat with 2 1/2 inlet/outlet and cut the one end to allow the 3 inch pipe to connect.
Its a little bit of fab work, we also install the heat shield that was there!

There was a long post of the forum about this, with pictures, dyno tests, and lots of good info!!

[stradman]

So here's the uncut graph. Three sets of runs all overlaid. Same dyno, same car.

2018-09-04 All Together.jpg

Stock Car Peak Numbers:
542.23 hp, 500.57 ft-lb
549.30 hp, 501.64 ft-lb
553.67 hp, 504.19 ft-lb

The temperature in the shop was +92°F. IATs not monitored.

Belanger Headers & Mufflers, with high-flow cats, no check engine light Peak Numbers:
555.73 hp, 509.51 ft-lb
535.49 hp, 505.84 ft-lb
541.20 hp, 504.90 ft-lb
556.05 hp, 516.46 ft-lb

The temperature in the shop was +73°F. Again, IATs not monitored.

Belanger Exhaust and Arrow Controller (canned tune) Peak Numbers:
560.70 hp, 512.51 ft-lb
548.85 hp, 515.59 ft-lb
543.84 hp, 508.98 ft-lb

The temperature in the shop was +90°F. No IATs.

SO,

I see no statistical significance in any of these numbers to definitively claim there was a power gain. The top run from each session was only separated by 7.03 hp, and when back to back runs in the same session differed by as much as twenty horsepower, I can't see a reliably-measurable difference.

2018-09-04 Best Of Each.jpg

The red line in the above graph is the Arrow line. There's a massive apparent loss of power between 4,200 rpm and 5,000 rpm, and the peak power only happens north of 6,000 rpm. You can't see this in the "all in one" graph, since it's lost in the noise.

Where am I going with this?

Nowhere.

I like the sound of the Belangers and I really like the pop of the Arrow. The sills are only warm to the touch, the skip shift is gone, and the car feels smoother to drive and shift at all speeds. Even the Dyno tech asked what I'd done to it since it sounded so different when he fired it up. I don't think any of these mods are a waste of money and not worth doing. My biggest takeaway from this, since I'm relatively new to dynoing things, is that if you can't measure the same thing twice in a row and get the same answer, you just can't verify any claim of power gains. There's just too much experimental error here. You'd need an engine dyno in a climate-controlled lab to knock out some of the uncertainty.

To those of you who have dynoed your cars and reported numbers, have you only taken the best run? Do you see as much variance as I did during multiple runs? Do you have this big dip in power, consistently, around 4,700 rpm?

Interesting Bryan. I certainly am no mechanic, nor am I qualified to pass any valid comments on the above. However seeing this is the internet and anything goes, I'll talk out of my ass fwiw, with my thoughts. I noticed your car has circa 40k miles on it. Now I don't know what sort of mileage a lot of the other cars that have posted dyno runs have had, however surely your motor has been properly run in and loosened up after all these miles, and has therefore liberated/made the most of any tolerances compared to a newer engine-and I've been told this could amount to anywhere between 2 and 3% improvement in numbers- and for which could possibly account for your rather "healthy" stock numbers. So as your starting base is very good, perhaps due to your nicely "limbered" up engine, maybe the built in margins of tolerances that were originally there and were supposed to be "liberated" through the controller and the Belangers, perhaps have diminished leaving less available horsies to come forwards?? I don't know just an uneducated comment fwiw.....

[cubeman]

Interesting Bryan. I certainly am no mechanic, nor am I qualified to pass any valid comments on the above. However seeing this is the internet and anything goes, I'll talk out of my ass fwiw, with my thoughts. I noticed your car has circa 40k miles on it. Now I don't know what sort of mileage a lot of the other cars that have posted dyno runs have had, however surely your motor has been properly run in and loosened up after all these miles, and has therefore liberated/made the most of any tolerances compared to a newer engine-and I've been told this could amount to anywhere between 2 and 3% improvement in numbers- and for which could possibly account for your rather "healthy" stock numbers. So as your starting base is very good, perhaps due to your nicely "limbered" up engine, maybe the built in margins of tolerances that were originally there and were supposed to be "liberated" through the controller and the Belangers, perhaps have diminished leaving less available horsies to come forwards?? I don't know just an uneducated comment fwiw.....

A motor would lose horsepower rather then gain as mileage climbs. Tavarish just did a dyno on his crazy high mileage supra, thing rang in like 120RWHP. A 40k mile viper is a little too low to see noticable loses, but if someone dyno'd that 90k mile Gen V you might actually see a measurable HP lose if it's still stock. This can be attributed to carbon build up in the motor and various other factors. If anything I'd go far to say a brand new modern motor is running at 100% already.

[stradman]

A motor would lose horsepower rather then gain as mileage climbs. Tavarish just did a dyno on his crazy high mileage supra, thing rang in like 120RWHP. A 40k mile viper is a little too low to see noticable loses, but if someone dyno'd that 90k mile Gen V you might actually see a measurable HP lose if it's still stock. This can be attributed to carbon build up in the motor and various other factors. If anything I'd go far to say a brand new modern motor is running at 100% already.

Really? You're saying a brand new motor is stronger than a well kept, well broken in 40 k miler? What do I know, maybe you're right. I guess it would depend on what kind of miles, highway or city driving...

[Steve M]

Really? You're saying a brand new motor is stronger than a well kept, well broken in 40 k miler? What do I know, maybe you're right. I guess it would depend on what kind of miles, highway or city driving...

There's a point at which a new motor will loosen up some and produce higher numbers than one that hasn't been broken in, but at some point it will start trailing back off once things get a little more worn and the piston rings allow more blow-by. As you've already suggested, the mileage at which that happens depends on many things, so no one is really going to know where things start going south power-wise unless they religiously dyno their cars at set mileage intervals. For the most part (and this is just my opinion), Viper motors aren't highly stressed, and don't turn high RPMs, so "high" mileage shouldn't be as much of a factor, "high" being relative of course.

[Bryan Savage]

Brian,
Great write up. My graph is below; albeit a little different. We did make multiple pulls with each but unfortunately I don’t have those on my graph sheet. However I do believe we took the best of each.

1. Stock with full Belanger
2. Arrow with full Belanger
3. Torrie tuned with full Belanger ( this was the last pull and hottest time of the day )

Interesting that our Arrow pulls are almost identical.

The Belanger and Arrow peaks do look similar! That Torrie number is pretty awesome tho!

On the dyno, or on the street? The gains from those mods shouldn't be in the noise unless you have something else going on with your build...a full bolt-on Viper should be substantially faster than a stock one, like in this clip:

I'd take a good hard look at your Belanger "high flow" cats. Any guess as to how he got them to not throw a CEL with the stock PCM? I have one...

Lou Belanger prided himself on his system, with cats, not setting a check engine light, and he was absolutely right. I did set one when I pulled out wires, but it's been fixed for a while, and nothing. Your MIL on for a different code? I threw P0139 "O2 Sensor Circuit Slow Response", P2270 "O2 Sensor Signal Stuck Lean", and P1E09 "Manufacturer Defined" and figured out this was the culprit:

2018-07-04 O2 Sensor 2.jpg

I would very much enjoy squaring up to a stock Gen V for a couple of "rolling dyno" pulls. That would definitely clean up the airflow and any potential intake temperature concerns. Note that on the stock pulls, the car gained power with each pull (or at least showed it did), and it was a hot day, so heat soak schmeet soak on that one!

Also... owned. lol

Viper TA Tune.jpg

Do you have a pic of the Belanger high flow cats? There seems to be a couple different high flow cats from Belanger, and some of them are stock non high flow.

The Stage 1 controller actually leans the car slightly since the factory program errors on the rich side for safety. The main purpose of the stage 1 controller is so you can do modifications to the car and the computer will allow it, without going into limp.

The thing i see missing from all the information is the AFR charting with the pulls, might add to the story!

Here's a pic of the system. I ordered high-flow cats and the sills barely get warm now, so I believe it. Can you tell from the photo?

Belanger Cat.jpg

No AFRs, Scot!!! I'm not that sophisticated!! Perhaps I ought to swing out your way again and have yinz try your dyno??

Interesting Bryan. I certainly am no mechanic, nor am I qualified to pass any valid comments on the above. However seeing this is the internet and anything goes, I'll talk out of my ass fwiw, with my thoughts. I noticed your car has circa 40k miles on it. Now I don't know what sort of mileage a lot of the other cars that have posted dyno runs have had, however surely your motor has been properly run in and loosened up after all these miles, and has therefore liberated/made the most of any tolerances compared to a newer engine-and I've been told this could amount to anywhere between 2 and 3% improvement in numbers- and for which could possibly account for your rather "healthy" stock numbers. So as your starting base is very good, perhaps due to your nicely "limbered" up engine, maybe the built in margins of tolerances that were originally there and were supposed to be "liberated" through the controller and the Belangers, perhaps have diminished leaving less available horsies to come forwards?? I don't know just an uneducated comment fwiw.....

It's definitely a thought! Unfortunately, I didn't do anything to measure when the car was younger. And hell, with as noisy as these dyno numbers all are, I'm not sure anything would show if I had a run at 1,000 miles, you know?

A motor would lose horsepower rather then gain as mileage climbs. Tavarish just did a dyno on his crazy high mileage supra, thing rang in like 120RWHP. A 40k mile viper is a little too low to see noticable loses, but if someone dyno'd that 90k mile Gen V you might actually see a measurable HP lose if it's still stock. This can be attributed to carbon build up in the motor and various other factors. If anything I'd go far to say a brand new modern motor is running at 100% already.

Buuuuuut I'm thinking every Car and Driver, Road & Track, and Autoweek magazine I've read shows every car being faster at the 40,000 mile mark than it was new. I would agree with the losses once you near the 100K mark, which I'm in a race with Bruce H. to get to, but I would agree that it's a little early to lose much power.

[98intrigue]

Hey Bryan,

I did a stock dyno and then the same mods as you within 2 weeks on the same dyno. Very similar IATs and power gains were 60whp/40wtq. I know different dyno, different days, too many variables. Car trapped 126mph stock and then 133mph with all the mods. I’m sure the IATs has something to do with that as well though, as I trapped 133mph in perfect FL winter weather.

I also did a back to back on my stock ACR and then with the Arrow PCM. Gains were 20whp and I forget the torque. Pulls were done within 20 mins of each other.

Just some data to compare against.

[Jack B]

So here's the uncut graph. Three sets of runs all overlaid. Same dyno, same car. If you use zero smoothing

2018-09-04 All Together.jpg

Stock Car Peak Numbers:
542.23 hp, 500.57 ft-lb
549.30 hp, 501.64 ft-lb
553.67 hp, 504.19 ft-lb

The temperature in the shop was +92°F. IATs not monitored.

Belanger Headers & Mufflers, with high-flow cats, no check engine light Peak Numbers:
555.73 hp, 509.51 ft-lb
535.49 hp, 505.84 ft-lb
541.20 hp, 504.90 ft-lb
556.05 hp, 516.46 ft-lb

The temperature in the shop was +73°F. Again, IATs not monitored.

Belanger Exhaust and Arrow Controller (canned tune) Peak Numbers:
560.70 hp, 512.51 ft-lb
548.85 hp, 515.59 ft-lb
543.84 hp, 508.98 ft-lb

The temperature in the shop was +90°F. No IATs.

SO,

I see no statistical significance in any of these numbers to definitively claim there was a power gain. The top run from each session was only separated by 7.03 hp, and when back to back runs in the same session differed by as much as twenty horsepower, I can't see a reliably-measurable difference.

2018-09-04 Best Of Each.jpg

The red line in the above graph is the Arrow line. There's a massive apparent loss of power between 4,200 rpm and 5,000 rpm, and the peak power only happens north of 6,000 rpm. You can't see this in the "all in one" graph, since it's lost in the noise.

Where am I going with this?

Nowhere.

I like the sound of the Belangers and I really like the pop of the Arrow. The sills are only warm to the touch, the skip shift is gone, and the car feels smoother to drive and shift at all speeds. Even the Dyno tech asked what I'd done to it since it sounded so different when he fired it up. I don't think any of these mods are a waste of money and not worth doing. My biggest takeaway from this, since I'm relatively new to dynoing things, is that if you can't measure the same thing twice in a row and get the same answer, you just can't verify any claim of power gains. There's just too much experimental error here. You'd need an engine dyno in a climate-controlled lab to knock out some of the uncertainty.

To those of you who have dynoed your cars and reported numbers, have you only taken the best run? Do you see as much variance as I did during multiple runs? Do you have this big dip in power, consistently, around 4,700 rpm?

If you have the file plot rpm and mph, it looks like you are slipping on the rollers. If you use zero smoothing your trace will get real ugly. I have done four or five sessions and my car has slipped drastically except in the last session which was at Arrow.

[cubeman]

I would love to see if you swap out the cats what your gains are, I can't personally believe the cats are holding back 50rwhp.