Blacksmoke

What is the difference between 3' and 2.5' tubing be?

As in.. what kind of difference does it make as far as sound and performance?

Is it a no no to get 2.5 with a catback system?

BlackStang21

[align=left]The only difference is the size of the tubing. It may results in a little performance increase because of the extra space that is created, but this may only be noticable by F/I and not N/A.

To your second question. There is nothing wrong with getting a 2.5" catback system. Your stock pipe is 2.5" so there is no difference. I wouldn't recommend getting the catback system though unless your going with the Pypes midmuffler, because it'd otherwise be a waste of cash when you could save and just buy the axlebacks.
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Blacksmoke

Well.. I got the catback because I know the guy at the dealership and he actually gave me the catbacks cheaper than he could get the axle stingers for.
The price for stingers just went up from the dealership plus he is a friend of mine.

157dB

The exhaust on the GT is properly sized and going bigger
is not always better.

Nuke

I've heard but can't confirm that going from 2.5" to 3" may result in some loss of torque. Hopefully, one of the "experts" can provide some feedback.

UberHax0r

I'm not an expert, but I believe this to be true for nearly all IC engines. they need back pressure. now with s/c cars, a larger exhaust can help as the back pressure from 2.5" can be less efficient (but certainly not harmful). with turbos, sizing is especially important because too much back pressure can cause the turbo to spool slower/not produce as much boost.

at least that's my understanding [8D]

howarmat

I would agree with this

Z06 Killer

With your set up going to a 3 inch, you would loose a bit of torque. And the exhaust note will get a little more raspy and poppy. I have dynoed 3" on a supercharged mustang right after pulling a 2 1/2" and even a blown motor seen next to no gain.

Besides. I thought you already purchased an exhaust according to your other 30 threads! Just be happy with what you have. All you need is 2 1/2" with the appropriate mufflers of your choice for your sound preferance. If you go with a full exhaust or an o/r pipe or 3" you are just throwing your money away.

modaddict

You are correct, sir. Not wise n/a IMO.

ANBAUTO

Ill post my dyno sheets up for you guys i just gotta find it. I went from the stock h and stock exhaust to a magnaflow catted x and 3" catback i did pickup more hp and tq