I was considering just getting rid of the restrictive exhaust as opposed to getting a full cat-back. Does anyone think that the extra pipe from the resonator will do anything? I am thinking that a hi-flow muffler should give about the same gains as a cat-back. A couple places around here have Magnaflows for a good price. I would imagine it's similar to some of the cat-backs that are available.

I did a search and couldn't find this: What's the stock exhaust size?

Any responses are appreciated.

 

The stock exhaust is 2.5".You live in Portland




Evo mods:HKS downpipe,K&N drop in filter,JIC TI exhaust,Wheels Racing Hart CPO-35R 18x9 be here tues,Soon to be TEIN or JIC coilovers can't decide????????

 

I do live in Portland and we have talked (at Baxters on McLoughlin). I found the reference in Claudius's "Engine Tuning" post to a 63mm exhaust after I made this post. 63mm equates to slightly less than 2.5.

So, is my logic sound? What exactly would I gain from having the extra X feet of tubing between the resonator and the muffler? Are the gains we are seeing from cat-back installs primarily related to removing the stock muffler?

 

I believe that the improvements are a combination of 1) better muffler (see Pruven's axel-back system) and 2) improving flow to the muffler through either larger 3"pipe, removal of restrictive bends in the stock design, or a combination of the two.

 

Actually, I got it on a lift and had a chance to scope it out. The muffler doesn't appear to be too restrictive from the outside (don't know what's happening inside). There do appear to be two resonators in between the cat and the muffler though. I would imagine that those are the source of restriction/turbulence. So, it looks like a high flow muffler wouldn't be worth much.

 

Which would the different gains be between a 2.5" downpipe and 3" downpipe? Will top end be significantly better with a 3"? Or will it be pretty close with a 2.5" and have better midrange?

This is still pretty much on topic