Gen3 4 exhaust manifold vs headers

[firefighter196]

Hi guys I'm looking for some advise I took the exhaust manifold from my car to 2 different exhaust places to get there opinion, here is what they said. They did not believe there was enough restriction and that they were very well constructed along the lines of a shorty headers, and they thought I was better off using them along with a true 3" flex section and 3" high flow cats in the original spot in the wheel well and then 3" pipe to the 3' mufflers I have. The other option I presented to them was headers and cut the 3" high flow cats into the turnout pipe which would put the cats into the sills and also the O2 sensor in the sill and then 3" pipe to the 3" mufflers. They thought the flex section was important and the heat generated by the cats in the sill could be a problem. Am I winning or losing very much with either option, the original manifold does have a 3" outlet. Looking forward to your views thanks.

[Steve M]

I'm in the process of trying to figure that out actually, but it's going to be a slow process. I'm currently trying to see what I can get out of the stock exhaust manifolds, high flow cats (3" in, 2.5" out), and stock mufflers. Now that tuning software is available for the Gen 4s, you can optimize the tune for all mods, whereas before you really needed headers to get the most out of the Mopar/Arrow PCM since they were tuned specifically to run with headers. I'm sure there are some gains to be had with headers, but I have yet to see a before/after dyno (or time slip) showing the difference with both tuned to their maximum potential.

I'm not sure about the Gen 3, but the Gen 4 stock cam exhaust lobe is pretty weak. Specs here:

I would like to get a cam for it. The stock cam is not what we'd usually consider a performance cam. The intake lobe is pretty good. It's 230 @ .050. But the exhaust lobe is very weak. It's 223 @ .050", and it gets worse. It only has .465" lift at the valve. That's not a typo. .465" exhaust lift.

Those numbers are from a Gen 5 cam, which from my understanding has a more aggressive intake lobe, but the same exhaust lobe.

[pony23]

I went with headers and a true 3" exhaust. I moved the 3" cats to the sills. Custom exhaust that I made so I got what I wanted. You will need extension wires and 90 degree adaptors for the O2 sensors. The 3" pipe is too large and the sensor hits the sill piece.

[Rocket]

And it would appear that most of the aftermarket header/full exhaust systems did not have the flex coupler that the shop was concerned about. It certainly could not hurt if they felt that strongly about it and if you did not go aftermarket headers. BTW - Gen 3 or 4 and what other mods are you doing?

[firefighter196]

My car is a 2004 srt10 the mods I'm doing now are A/C Performance stage 3 heads and cam package with there variable timing chain along with a swing arm oil pickup and pan. I have M&M headers I can put on and I have Vibrant Performance high flow cats and 3" Billy Boat exhaust and 355 gears.

[Rocket]

And you are planning to tune the engine using ......? You're putting on heads and cam to help it breath better and even debating on headers and a high flow exhaust? Seems counter-intuitive to me even knowing that the Gen 3 seems to like a little back pressure and a lot of reinventing what has already been tried and true. Moving high flow cats to the sills is also done regularly without issue.

[firefighter196]

Thank you for the input I have to agree with you I should not be reinventing the wheel, I have the headers and will put them on. I will just have to figure how to put the O2 sensors in the sill, as for tuning Todd at A/C is going to be doing the tuning as it is his kit and I think he is one of the best.

[Steve M]

With those planned mods, headers are a no-brainer.

[Mopar'er no car]

Not sure if this helps..

I plan on the Gen 4 conversion upgrade in the future. I had always planned on putting headers on the Gen 4 heads. My mind changed when talking to Lee from Arrow. He made a very good point in saying, " For the 25 extra HP after the conversion why would I want more heat in the cabin with headers"?

"With 3 inch exhaust, cat delete ( or high flow ) it's not going to sound any better with headers"

"All for an extra 2-3k, I'm getting to old for that..l0l"

Lee has a Gen 3 vert with the Gen 4 upgrade running the stock gen 4 exhaust manifolds.

[Vprbite]

I did Belanger coated headers and high flows and corsa and noticed power right away. I spun my tires leaving the tech's shop by going to the same throttle position as I had before. Also the sills run cooler than cars without them. But when it's 104 out here, well, ain't nothin gonna help much to cool them. But it was 70 out the other day and after an hit drive you could get right out and grab them.

I feel like the shifter bezel might get a bit hotter than it used to but that could be in my head. But would make sense with the headers right there.

The setup I went wih is nothing new or experimental and is what our tech usually recommends and runs on his car. Jon also recommended it to maintain torque (if I was doing F.I. We would have gone with the 3" I believe is the difference) but for NA he said this would not be torque robbing, which goes to what rocket was saying.

I also really like the sound. I can post YouTube links if you would like. I have recordings outside and inside.

Good luck!

[Rocket]

An extra 25 hp is a big number and I don't believe that the headers are a source for cabin heat. Most of the heat is caused by the cat converters (especially the nuclear-temp stock cats). If you mount the cat before the turnout, those cats are right at your feet. Eliminating the cats brings bad smells into the cabin, so I'm a fan of high flows.

Not sure if this helps..

I plan on the Gen 4 conversion upgrade in the future. I had always planned on putting headers on the Gen 4 heads. My mind changed when talking to Lee from Arrow. He made a very good point in saying, " For the 25 extra HP after the conversion why would I want more heat in the cabin with headers"?

"With 3 inch exhaust, cat delete ( or high flow ) it's not going to sound any better with headers"

"All for an extra 2-3k, I'm getting to old for that..l0l"

Lee has a Gen 3 vert with the Gen 4 upgrade running the stock gen 4 exhaust manifolds.

[Mamba003]

Headers on a stock Gen III aren't going to do much aside from burn up everything if the wires are moved. For a GenIV or GenIV conversion there is some real improvements power. My Viper Specialty VSX700 build included GenIV stock heads, ported manifold, a mild cam and Bellanger headers/full exhaust, did 613 to the wheels. Prior to that build it did 503 to the wheels with all bolt ons aside from headers.

[Mopar'er no car]

An extra 25 hp is a big number and I don't believe that the headers are a source for cabin heat. Most of the heat is caused by the cat converters (especially the nuclear-temp stock cats). If you mount the cat before the turnout, those cats are right at your feet. Eliminating the cats brings bad smells into the cabin, so I'm a fan of high flows.

I'm not going to lose sleep over 25HP. And yes adding headers will create more heat. It's not noticable usually because most if not all install high flows or remove them when doing headers. By design it's going to create more heat, plus your removing the heat shield..Your also moving the heat source closer to other items as the manifolds are much more compact.

The Cast iron holds heat while the headers just transfer it. This helps the cast iron expel more heat rather than transferring it onto other objects.




Removing the cats all together is also a no go for m...That exhaust tip is less that 45 inches from my face...l0l

[SNKEBIT]

Gen 3&4 don't have cast iron manifolds. They are SS. On a gen 3 you can put the stock shields over the headers if wanted. You can move the wires so they don't get burned. Have done this install many times. Headers with high flows way cooler than stock set up and more power!!

[Mopar'er no car]

Gen 3&4 don't have cast iron manifolds. They are SS. On a gen 3 you can put the stock shields over the headers if wanted. You can move the wires so they don't get burned. Have done this install many times. Headers with high flows way cooler than stock set up and more power!!

I keep thinking Truck. Forgot about the tubular manifolds..


I still don't see as huge as an increase like everyone thinks by swapping headers..More in the restrictive stock cats and mufflers..

A few ponies up high, looks good on a graph that's about it.

[Rocket]

So curious - why go the Gen 4 upgrade route?

I'm not going to lose sleep over 25HP. And yes adding headers will create more heat. It's not noticable usually because most if not all install high flows or remove them when doing headers. By design it's going to create more heat, plus your removing the heat shield..Your also moving the heat source closer to other items as the manifolds are much more compact.

The Cast iron holds heat while the headers just transfer it. This helps the cast iron expel more heat rather than transferring it onto other objects.




Removing the cats all together is also a no go for m...That exhaust tip is less that 45 inches from my face...l0l

[Mopar'er no car]

So curious - why go the Gen 4 upgrade route?

I just like the look of the valve cover covers....l0l

700 Crank HP. Was going to go down the header route until talking to Lee from Arrow..

90HP drivetrain loss on your car? Seems a bit high..