Exhaust

[STOCK94]

Got a question, on the 05-08 do you need the back pressure of cats. for better performance or do you get more from off road pipes, I bought my car it already had a blower and long tube headers right now It's got a mid pipe with one cat on each side and the flowmasters in the back. Would an off-road pipe help or hinder, not taking into account emmisions.

 

[blackgt460]

I'm sure it wont make a huge difference since they are small high flow cats but there only one way to find out. It would be a simple change especially with the long tubes probably a half hour job including jacking the car up.

 

[SpartaPerformance]

Think of an engine as air pump.....the less restriction between intake and exhaust the better it works. No they don't need backpressure...that is a topic very misunderstood by many. You can remove the cats for better performance however the car will get a lot louder and will change the sound of your mufflers as well so be ready you may not like it.

 

[whyask]

Depending on were you live you MAY need the cats. so check with you local laws first so you dont get unwanted friction from the locals boys in blue !

 

[NastyStang113]

Removing the cats will increase power. Typically 2-4 rwhp. However I wouldn't do it unless you plan on switching to another muffler. I've heard a car with a O/R Mid Pipe and it sounded like crap with the Flowmasters.

 

[PSYKOSTEVO]

Removing the cats will increase power. Typically 2-4 rwhp. However I wouldn't do it unless you plan on switching to another muffler. I've heard a car with a O/R Mid Pipe and it sounded like crap with the Flowmasters.

Mine sounded like crap with magnaflows too. That's why I have no more mufflers. Now the only complaint that I have is a strange rasp between 2,000-2,250 rpms but it's gone as soon as I get up past 2,250.

 

[Sparty92]

Mine sounded like crap with magnaflows too. That's why I have no more mufflers. Now the only complaint that I have is a strange rasp between 2,000-2,250 rpms but it's gone as soon as I get up past 2,250.

I'll bet you a dollar that is the noise I had on my 07 GT. It's the shield on the bellhousing. It vibrates between 2-3K....sometimes a little higher. There's a TSB floating around there for it, if you search. The original TSB has them cutting off a exhaust hanger isolator. Doesn't work. I tried it. The OTHER TSB wants them to drop the trans and fix the shield on the bellhousing.

The tech at my dealer was "aware" of this problem on the trucks, so he suggested a little foam tape in between the shield and the housing. This worked like a champ. Buzz rattle is gone.

Good luck.

 

[Nemesis4.6]

I'll bet you a dollar that is the noise I had on my 07 GT. It's the shield on the bellhousing. It vibrates between 2-3K....sometimes a little higher. There's a TSB floating around there for it, if you search. The original TSB has them cutting off a exhaust hanger isolator. Doesn't work. I tried it. The OTHER TSB wants them to drop the trans and fix the shield on the bellhousing.

The tech at my dealer was "aware" of this problem on the trucks, so he suggested a little foam tape in between the shield and the housing. This worked like a champ. Buzz rattle is gone.

Good luck.

How did you install the tape ? Where do you do it? Im a retard when it comes to that but I think I have that buzz/rattle.

 

[STOCK94]

If it's not worth any more horses than you guys say and it'll make it sound like crap then it aint worth it till I hit a point I can't get any more power. Thanks for the answer/advice.

 

[DarkFireGT]

Actually, the removal of cats on a blown engine might net some decent numbers. Off Road H's are good for 6-8 RWHP on a NA car. Off road X's are worth 7-11RWHP on a NA car. For forced induction, that number would have to be higher, especially with headers. But how much will depend on what kind of cats you have right now. If they're like the stock ones, you'll gain a decent amount. If they're high flow, you'll probably only gain what NA engines gain.

 

[NastyStang113]

Really? You've seen that much of a gain? Any examples, details?

I've only ever seen ~2-4 rwhp on a N/A car and numbers like ~8-12 on a boosted car.

 

[PSYKOSTEVO]

I'll bet you a dollar that is the noise I had on my 07 GT. It's the shield on the bellhousing. It vibrates between 2-3K....sometimes a little higher. There's a TSB floating around there for it, if you search. The original TSB has them cutting off a exhaust hanger isolator. Doesn't work. I tried it. The OTHER TSB wants them to drop the trans and fix the shield on the bellhousing.

The tech at my dealer was "aware" of this problem on the trucks, so he suggested a little foam tape in between the shield and the housing. This worked like a champ. Buzz rattle is gone.

Good luck.

Good looking out, I'll try that.