Best Exhaust for a 3400 P&P Engine?

[blackbombshell95]

i have a 95 grand prix 3100. i'm doing the top end swap. i just purchased a 3400 upper and 3400 throttlebody both ported and polished. and tomorrow i will purchase the lower. and next week i will get the heads.

my question is what size exhaust piping would be adequate? i'm guessing 2.5'' from the downpipe to a 2.5'' highflow cat, no resenator, and 2.25'' piping at the Y? how does that sound to go with my engine?

do u know of any brand/model catback that would be a good choice. and are they any good mufflers that I should get along with a cat?

i'm looking more on the performance side. with a little bit of a deep v8 like sound(not SUPER LOUD hopefully), although i know it will be very loud.

i already have straight flow JKL dual mufflers on right now.

any input will be appreciated.

[v6h.o.]

yeah i would go with 2.5inch piping. you really dont need to do 2.25 dual Y at the back. a 2inch Y for the mufflers would suffice.

[blackbombshell95]

ok. i already am using 2.25 dual y piping though.... so what kind of cat-back would be the best? what brand? would a 3'' high flow on a 2.5'' pipe be better or use the same size cat as the piping?

[donk_316]

Dude, the exhaust your discribing would flow well enough for a good street small block. 2" all the way is more than enough for a 3.1

[v6h.o.]

there are no aftermarket "catbacks" in larger diameters. you'll have to get an exhaust shop make one.

if your putting on a highflow catalytic converter do the same diameter as the rest of your piping.

[blackbombshell95]

ok. i know if i buy a high flow cat back from a local exhaust shop they are going to get some good markup on teh product. i want to save money and buy a catback and bring it to them and have them put it on.... so sincee i'm going to go with 2.5'' piping, am I alright to buy a highflow 2.5'' magnaflow catback off of the internet??

[blackbombshell95]

what is teh factory exhaust piping for my 3100?

[ikessky]

The factory piping is probably a 2.25" downpipe and 2" after the cat. A mandrel bent 2.25" system would flow just fine for your combo. Unless your cat is bad, don't bother with a "high flow" model. They flow the same as a '95 OEM cat. CatCo universal high flow's are cheaper than OEM stuff though.

[blackbombshell95]

so a magnaflow highflow cat wont do much performance wise with new 2.5'' piping?? but anyways what if i buy one from ebay and bring it in to a muffler shop and have them put on new exhaust piping with the cat?



how about this cat?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7907549996&category=33629

should i buy this one and bring it in to the muffler shop when they do my exhaust?