(take 2)

I installed Downey headers on my 3vze, which collect via crossover into a 2.5 inch y pipe. After that is a total mess, though. The stock muffler is rusted through, most of the original piping isn't far behind, and the catalytic convertor has bits falling out of it.

I want a new muffler, and I've read 2.25 is the optimal sized pipe for the 3.0, but does this mean for piping following the muffler or all piping following the headers?

I'd like to keep the pre-existing 2.5 y pipe, if possible, based solely on $$$. I could get new 2.5 pipe from the y-pipe, straight to the muffler (disregarding the cat as one isn't required in my area), then 2.25 out. I could also get a new y-pipe with a 2.25 collector instead of 2.5, then run 2.25 all the way to the muffler and out.

Are there any concerns with a smaller outlet than inlet diameter, because if so, I could just buy an exhaust adaptor (2.5 to 2.25) that would mount directly after the 2.5 y-pipe so that the muffler would be 2.25 in and out, but if there is a better way, I don't know it, and research isn't clear enough to provide it.

Thoughts?

 

With the 3.0 I don`t really think much will change no matter how you do it.

Go with what is the cheapest for you.

In the past I ran all kinds of strange exhaust systems. 2" muffler inlet with 2.5" coming out

Stock 1.75" to 2.25" after the cat.

In the big picture I can`t see it really doing anything but it seemed a good idea at the time. Or the parts where on hand.

Now if this was a race vehicle some thought into the exhaust might be worth while.

 

My cat was glowing red after driving only 30min. I'm debating whether to gut the cat and run straight pipe with no cat or to just replace the cat? I am only concerned about performance, not sound. How will gutting the cat hurt or help the performance? Any advice? Thank you for any help!