Can someone tell me the diameter of my GMPP Exhaust and the dimensions of the GMPP Manifold? I looked online for about 20 minutes but couldn't find any numbers...and I don't want to go out to my car to measure

I'm trying to figure out what down pipe size I need

 

the exhaust is 2.25

 

Ugh...so a 2.50 DP wouldn't fit snug

 

i dont think youll have an issue, its only amounts to like a 1/8th inch difference, im sure if the gasket will seal it just fine....

 

What about the exhaust manifold? Do you know the primaries and collector dimensions?

 

I cant find it, try PMing CED and see if they can tell you

 

A 2.5" DP is perfect for our GMPP catback and exhaust manifold. I have both and xtc 2.5"dp and no leaks yet. Had the dp on for about 6K miles now.

 

Did you notice a difference in gain from the dp?

 

this is from his sig

 

You might notice a slight gain, but I think the exhaust manifold is the largest gain department, that and the cat-back. Our DP's aren't that small, and there aren't a whole lot of bends.. The stock cat and like one smaller section in the DP maybe about it for restrictions.

 

A slight gain? Well for $230 bucks I better see more than that

 

Gains per exhaust piece should net approx. 5-7whp...from what I hear from talking to a local SLP exhaust rep. Combined, you will get a nice gain, but if you already have the cat-back and are adding the manifold and DP, then I don't see you netting much more then 10 or so whp, especially since it's the GMPP manifold and not a true header

 

I have the GMPP manifold...so I need to get a real header?

 

so a gmpp honed manifold would be a good upgrade and will notice power

 

I have it

 

i knw u have it,im askin bout me...my b-day comin up and i gotta see wat i should get...gmpp mani or zzp header

 

you would see better gains with the zzp or cobalt-addiction header

 

X2^^ A true header will give much better gains then just a honed manifold.

 

I just did a search on this topic...a lot of misinformation here and there. Someone should post some facts and make it a sticky

 

Misinformation on this site, nah...lol

Keeping in mind the difference in assembly of the honed manifold as opposed to a true header, you can see the piping and flow openings on the headers will outperform a honed manifold any day of the week

 

so hp gain will go up,psi MIGHT go down,but car will pull harder...how much louder will the exhaust note be if im on the stock muffler..

 

The tone should actually deepen slightly with the stock muffler from what I understand.

 

i was thinkin the same thing,since u opened up the beginning of the exhaust,and the rest is opened already

 

So should I ditch my manifold and get some headers?

 

you could probably recoupe most of the $ you spend on a new header by selling the GMPP one on here