I asked this question several months back...

"Would it be beneficial to run a 2.5" downpipe to a 3" collector before the cat, and run 3" the rest of the way back, so that I could have a 3" exhaust if/ when I turbo the car?"

I received a bunch of good feedback saying to just running 2.5" all the way


Now to my new question...

Since the H.O manifold has a 2" collector, it really shouldn't matter what size my exhaust is, since the consensus is that "Your exhaust will only flow as well as it's smallest part." Having a fair understanding of fluids, I would have to agree with this statement. However, theoretically, this should mean that I could run a full 3" exhaust all the way back, since the scavenging effect stops at the end of the manifold. I will be running a cat, so the way I see it, is that there is more surface area in a 3" cat to lessen the restriction of exhaust gas flow and help improve emissions. Also, I should be able to run a round 18" Magnaflow glasspack muffler (to use as a resonator) with a 6" OD (assuming 6" will fit under the car) to help deaden the exhaust note more than a 2.5" can at idle.

I would also like to hear from those that have a 3" exhaust. I have heard before that you guys/gals have had problems with it hitting the rear "axle" (I know it isn't an axle, just a loss for words right now). If that is the case for all of you, is it possible to wrap that part of the exhaust or the "axle" with a significant amount of header wrap, then spray it with the high temp header wrap sealant to reduce the impact and unfortunate ping or dong sound that follows?

In case you were wondering why I am so adamant about having a 3" exhaust (and I know you are): it's because I am cheap, and don't feel like spending money on the same mod twice. I only have a few years left with the cav before I move on to bigger and better things, and I would like to enjoy them as much as possible (bulletproofing the motor has taken 8 months away from me driving it alone, and with the exception of a few minor water hose fittings, the exhaust and a little bit of tuning, it is about to see the light of day again)

On a side note, if I do intend to boost, it will be somewhere from 8-12 psi (high compression gets nervous under pressure). I don't intend to change out the pistons again so that I can get 500 whp running 25psi and blow up my transmission.

If you are confused by anything I am asking, please feel free to ask. I know my mind sidetracks a bunch, especially after midnight (which is consequently the time when I wrote some of my best bs papers in high school).

Brian

Sorry... 30" resonator is about 20 dollars more, so I would go with that instead of the 18".

You know what, screw it. I'm just going to port the manifold at the collector a bit and do the full 3" exhaust and deal with whatever the end result is. Sorry to have wasted your time. Later

Brian