Best exhaust size

ghettogmc91

ghettogmc91

New member
Ok its not a Typhoon but i know that if anyone can help with my question it would be on here.

Right now i have a 91 S15 4.3 with vortec heads, 2114 intake, Edelbrock headers, cat delete, Magnaflow 2.5 muffler, powerdyne supercharger, and other stuff that doesnt matter to this post lol.
Right now with the setup it pushes about 5psi anytime i get on it a bit. The problem is that almost anytime i hit 5psi it blows my tailpipe off the muffler. After it does this it seems slower but builds up to about 6-7psi boost.
It currently has a 2in tailpipe because i thought it would help with the exhaust flow but now im wondering if its undersized and causing a problem. So im wondering if you guys would recommend a different size. Ive seen 2.5 and 3 listed alot on here but didnt know if it would be worth it at only 5psi.
 
SY2455

SY2455

70's Veteran
Re: Best exhaust size

If you went with a 2.5 muffler then you should of stayed with that size all the way out the back. You are choking that engine by going down to a 2" tailpipe. On my daughter truck we went with a 2.5 system from the cat back. On our Safari van we went with a 3" cat back. Let that thing flow.
 
Beavis

Beavis

Still plays with trucks
Re: Best exhaust size

You arent gonna hurt that thing if you run a full 3" from the Y pipe out.
If you are blowing it apart, it NEEDS to be bigger.
That is the best flow you are gonna get for that.

I ran a full 2.5 on my '89 jimmy with no cat and a straight through muffler on a stocksih motor and it loved it.
 
ghettogmc91

ghettogmc91

New member
Re: Best exhaust size

Ok. I was just afraid that going too big would make it slower because it wouldnt be as efficient. I guess ill jus take my tailpipe off n have one made in 2.5 or 3 rather than try to find one this time tho lol. Thanks for the info
 
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