Jason in Vancouver

Will muffler add torque or only horsepower?

carl [i has type-S]

horsepower is a mathematical function of torque. if one goes up, the other does too.

woofpup

3.0 or 1.8T? Stock 3.0 will lose some low end but gain a few HP in the upper range

Oaktree

Repost:
Perhaps the most popular first piece of speed equipment is the exhaust system. The gains of a cat back system are not super huge and mostly at high rpm. This is because of variance of muffler design even within one model year. It is impossible to spot by just looking at the car. If you have one of these restricted exhaust systems you can expect a big gain. If your engine is stock or if you are limiting yourself to bolt-ons, limit your pipe diameter to no more than 2" or you will lose some bottom end with no applicable gain on top. For turbo applications, 3" is the way to go. Unless you are turbo or nitrous only and are going for the maximum in power, do not bother with removing or gutting your cat. Unless the cat is melted it only has about 1.5 psi of back pressure or less and only affects power by 1-2 hp if that.
As far just replacing a muffler I would not expect a lot of gains. The piping is constrictive and does not flow well to the muffler. There is a good size indent before the muffler. I would assume you would have a more sound change than anything else. I would go cat-back if I were you going through the effort.

Hopefully, this helps somewhat. I am not sure if anyone has real world 3.0 performance statistics.

Big D

What do you know? Until Sunday, you still had the license plate on your front bumper! =)

B_Chicago

If you extended the redline you *could* get more HP without a gain in torque.

Auto Union Jack

A more appropriate question is where on the tach will the HP/torque go? North.

carl [i has type-S]

which was depressing in my case.

farking dealers.

Big D

Dude, some bondo, a little elbow grease, it's all good =)