My secondary cat delete DIY install

[stylin]

Decided to do the secondary cat delete and leave the primary cats in place. Just wanted a little extra sound volume. So now instead of having a quiet tractor sound, I now have a slightly louder tractor. Ha. I took it for a rip around the block, and it's noticeably louder with the windows down, but not so obnoxious that it gets old quick.

And I took the time to clean up the underside of the side skirts and polish the exhaust ports since they were blackened pretty badly. I was surprised that the metal exhaust plates came so clean, and it just took some Blue Magic, a polishing bit on my drill, and lots of elbow grease.

The cat replacement is a relatively easy install if you have a MIG welder. I had some old exhaust pipe laying around from a Mustang that was 2.5" and it worked perfect. You need a 14" section of straight pipe to make an exact fit and the 05-10 Mustang GT has the perfect section to cut out. If you cut the factory cat pipe where I marked in blue on the photos it gives the ideal flat spot for a good solid weld. The old Mustang mid pipe was a few years old and had a nice "patina" to it that matches the Viper piping, so unless you're really looking, you can't even notice that it's been deleted! Instead of a shiny new piece of pipe, it blends with the OEM pipe perfectly so no one will ever notice unless they know what they're looking for.

Biggest tip I have is to mark everything carefully for alignment so the exhaust tips and clamps go back in the correct angle. So you're not having to take the skirts off and on for fitment.

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After some cleaning:
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[ForTehNguyen]

what I like about the belanger kit is the tips are flush with the bezel so no more nasty cleaning in that area

[stylin]

what I like about the belanger kit is the tips are flush with the bezel so no more nasty cleaning in that area

That would be nice.

[Viper.954]

Did a CEL come on after removing the cats?

[stylin]

Did a CEL come on after removing the cats?

NO CEL. At least not yet. And it shouldn't because it's after the O2 sensors.

[simon455]

Secondary cat is just a “clean up” cat. It’s not monitored, as mentioned above, no downstream o2 from it

[stylin]

One more angle of my "patina" pipe after install.

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[ACR-ISH]

Very clean! Do you feel it made a noticeable difference in sound? Any freeway drone?

[stylin]

Very clean! Do you feel it made a noticeable difference in sound? Any freeway drone?
Definitely noticeable with windows down. With windows up, not much different. And no real drone at all. If you "gut" a cat, you can get a drone because of the large hollow canister that the exhaust goes through, but replacing with straight pipe does not.
It just sounds like someone turned the volume knob up a couple notches. At hot idle it sounds about the same really, although cold start was noticeably louder at the higher rpm. Now if I can just figure a way to do a Tractor Delete, I'd be all set. I need the John Deere removal mod (i.e. change the exhaust tone)

[ACR-ISH]

Now if I can just figure a way to do a Tractor Delete, I'd be all set. I need the John Deere removal mod.

Tractor Delete...? The popping? I may do this mod... I wouldn't mind the car being a little louder without messing with anything really. What size diameter and length were the pipes you installed, if you remember?

[stylin]

that info is in the original post.

These cars sound like a Tractor at low rpm. I've never been a fan of the stock mufflers.

[cashcorn]

tractor delete = headers + hi flow cats, stock muffler works & belanger muff is louder. nice right up, thinking about doing this for smog.. thanks!

[ACR-ISH]

that info is in the original post.

These cars sound like a Tractor at low rpm. I've never been a fan of the stock mufflers.

Duh. Not sure how I missed that. Thanks!

- - - Updated - - -


tractor delete = headers + hi flow cats, stock muffler works & belanger muff is louder. nice right up, thinking about doing this for smog.. thanks!

Ah. Gotcha. Thanks!

[JonB ~ PartsRack]

The DIY secondary cat delete should also provide some noticeable Sill Cooling.

THose of us with the earliest G1 and G2 cars had NO aftermarket parts to buy....

DIY did the job on my 93 and my 96 GTS. Good Post.

[ACR-ISH]

The DIY secondary cat delete should also provide some noticeable Sill Cooling.

THose of us with the earliest G1 and G2 cars had NO aftermarket parts to buy....

DIY did the job on my 93 and my 96 GTS. Good Post.

JON-

Do you recommend the removal as done above or the American Racing Hi-Flo cat for replacement pipe (which effectively does the same thing)? My car is under warranty so I'd like to keep the OEM stuff intact in case I need to swap it back on.

Anyone running straight pipe with just high flow cats...? I was thinking of doing the AR High flow with straight pipe... maybe a small resonator at the end... thoughts?

[nwa_viper]

I had my secondary cats cut off like this around a year ago. I carried them into a muffler shop and he charged me $20. Honestly one of the best things I’ve done to the car. A little louder sound and much cooler sills. I also had the PPF redone on the rocker after being melted from the secondary cat.

[ACR-ISH]

I had my secondary cats cut off like this around a year ago. I carried them into a muffler shop and he charged me $20. Honestly one of the best things I’ve done to the car. A little louder sound and much cooler sills. I also had the PPF redone on the rocker after being melted from the secondary cat.

Since I've pretty much copied your build thus far... :) I guess it's time to do this! I'm leaning toward the highflow AR cat since it deletes the secondary cat and it relatively cheap. Then I have all my stock pieces.

[ViperGTS14]

Looks like a great simple mod for sure. Shame there isn't a bolt-on option like high-quality clamps instead of welding. Then it could be done while the full exhaust is on the car unless it's not easy to cut the secondary cats off while still on the car, also supporting the muffler weight may be an issue for clamps?

BTW what does the inside of the stock muffler look like?

[ACR-ISH]

BTW what does the inside of the stock muffler look like?

Ooooo... good question!

[dewilmoth]

Ooooo... good question!

I believe Stradman has said it is a straight through pipe with a few perforations.

[txA&M08]

Now if I can just figure a way to do a Tractor Delete, I'd be all set. I need the John Deere removal mod (i.e. change the exhaust tone)

Simple: delete two cylinders and cross over the exhaust

[ViperGTS14]

Take this a step further, surprised someone hasn't come out with a header to muffler high flow single cat pipe yet. Not sure how much restriction the first cat's really created over aftermarket cats. Factory cats are pretty impressive for what abuse they can take.

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[ACR-ISH]

I thought they did make a hi-flow cat with secondary delete. I swear I saw one Weds and now I cannot find it.

[JonB ~ PartsRack]

JON-

Do you recommend the removal as done above or the American Racing Hi-Flo cat for replacement pipe (which effectively does the same thing)? My car is under warranty so I'd like to keep the OEM stuff intact in case I need to swap it back on.

Anyone running straight pipe with just high flow cats...? I was thinking of doing the AR High flow with straight pipe... maybe a small resonator at the end... thoughts?


PartsRack has NUMEROUS threads on here regarding our bolt-off-bolt on HF cat assys from Belanger. EZ search or: https://driveviper.com/forums/threads/23832-High-flow-cats-from-JonB-finally-installed-Should-have-done-this-long-ago?highlight=DOne+THis+Long+Ago

[ViperGTS14]

Curious if anyone has confirmed that gutting this secondary cat instead of replacing with a straight pipe actually does make a big difference the overall sound/tone or drone badly (more than it already does stock) also how it could negativaly effectively flow?

[Luco]

Do you smell the fumes?