I'm debating on just doing a muffler delete with a bent pipe to keep the stock look but add on that Boxer grumble or making a custom cat-back. If I go custom, what's the largest sized piping that I can use to gain the most performance?

 

good question. i noticed you commented on my thread so i'll return the look.
i think with doing anything like straight pipes you don't want to go nuts with the size. I would say 3 inch tubing should work well.
normally when youre allowing more exhaust flow you would need to adjust the other side of you engine to compensate, also for the full HP gain you should remap it.
i think even with 2 inch straight pipes your going to get that beautiful subie grumble, so i wouldnt go nuts.
since yours is N/A anyway maybe you could start from the last exhaust clamp (closest to the muffler) and see if you can hunt out some exhaust tubing that goes from your stock size into a 3 or 4 inch outlet. that would work just as good.
ive always been a fan of the N/A subie (its sort of slept on). Theres a kid in my area with last years model thats lowered with a front lip and a HKS exhaust and it looks and sounds amazing.
do you currently have any mods?

 

just found an interesting blog about N/As
hope this helps
http://dxpetti.com/?p=104

 

Oh wow, those are some nice rims. I love that front lip too.
As for my car, everything is stock, unless you count my hubcaps being removed as a mod =)
A friend of mine told me that if I want to get a custom exhaust, the largest I should go for a 2.5 liter N/A is 2 1/4 inch piping. 3 inches sounds awfully large to me, especially since the wagon only has one exhaust exit. The sedan has two, so it makes sense to make the rear section larger, but I don't want to lose that much back pressure.
Thanks a lot for the advice tho

 

word up, well keep us updated. i have about one more week to go before i can put mine on...
godspeed

 

Ya your wasting your time if you go bigger than a 2.25 in exhaust on n/a, all it is going to do is net you lost low end torque. I have not looked at the new subies yet, but the same thing applies as with previous gen subies, if you have el headers, your not going to get much of anything in terms of boxer rumble, its the headers and their shape that give the rumble, not the exhaust. Again, i dont know much about the new ones but it would seem to still apply.

 

I'm diggin' the rear spoiler lip! I wonder if these bits and pieces will actually get made.

 

From experience with prior cars, maybe, go with a more free flow muffler and a free flow cat, so that you don't loose too much back pressure. I've always had luck with Thermal Research. Nice sound and matched with a decent intake (not a Pep Boy special) you should see some HP gains. FYI the average aftermarket exhaust for the WRX models is 65mm about 2.5". Good luck!

 

Thanks everyone for the advice. As soon as there are updates, I'll try to post with pics and vids
I'm totally psyched for this. It bothers me that the car revs so high but that it's so hard to hear.