What diameter?

[KJ]

I am going to be putting a new exhaust on my 88 with the 2.9 V6. What setup should i use, diameter, muffler, etc.?

 

[JohnnyO]

It depends. I would use 2.5" pipe if you're doing a single system, 2" if you're doing duals. If you want duals it's easiest to use a single-in dual-out muffler instead of two mufflers.
Flowmaster, Gibson, and Magnaflow are all good mufflers. A 2.9 simply isn't a big enough motor to need a mess of big pipe.

 

[C_Root]

see above ^
Another option for a muffler is a Thrush Welded. Stainless steel construction, almost identical to a flow 40, and about 30 bucks through summit i believe. I have one on my 05 4.0L, and I like how it sounds, not over boarish, but a good low tone and a good sound when you give it the spurs.
Croot

 

[KJ]

Ya, the exhaust system is not going to be anything fancy. The current one is just rotting apart right now. I'll go with a single system. Any ways to get more power by messing with the exhaust?

 

[JohnnyO]

Any ways to get more power by messing with the exhaust?

A lower restriction muffler will get you around 5 to 8 hp. A 2.9 is a fairly small motor and too big a pipe, or true duals, will actually make less hp not more. Gibson's own numbers show an 8 hp gain with their single system and 5 hp with their single in-dual out system. Low restriction is good but you also have to maintain a certain velocity of the exhaust gasses.
You can either get a pre-bent cat-back system or have a muffler shop custom bend a 2.5" single system and put on a Flowmaster or generic turbo muffler or whatever.

 

[rusty70f100]

I don't think anything above 2 1/4" pipe will help with a 2.9L. I did 2 1/2" on a 4.0L and it sounded good though.

As for mufflers, I like the cheap thrush turbo mufflers. I tried straight through Magnaflow's on my old truck with a built 390 (see user name), and they made it slower than it was with the cheap turbo mufflers! Glasspacks had about the same affect on power as the Magnaflow straight through mufflers (and the same obnoxious noise) but were cheaper. The Magnaflow mufflers made it sound like a diesel about to throw a rod when I floored the gas.

Now my muffler findings might not translate to the smaller V6 motors, but I thought I'd share.

 

[KJ]

Ok, so i priced replacing the entire stock exhaust system and its about half as much as going with the 2.5 inch. I think that i'll just go with the stock and see if they have a decent muffler to throw on it. I hate the obnoxious glass pack or cherry bomb sound. Any suggestions with similar cheap prices?

 

[doorgunner]

single into the cat.....single-to-dual exhaust out of the cat....chrome Harley davidson motorcycle mufflers(gutted with a 2" steel-cutting hole saw attached to a 20" long extension) exiting at the bumper....closest sound you'll EVER get to a V-8...

 

[schneiderz]

just straight pipe the exhuast my friend did that and it sounds pretty good.