straight down pipe

[Ronsam2006]

You'll probably make a significant amount of boost over what you normally run (derestricting your snail), since if I'm right honda downpipes are real short, so there's very little backpressure. This is good if your motor can handle it, bad if you're pretty close to the boost limit on the internals setup you have. I'm also assuming you're catless. I say that because I've run the WRX with an open downpipe before and the car ran very strong compared to with the catback on, but the stock downpipe has 2 cats in it and is only 2.5in (backpressure galore) which probably is what prevented serious boost creep. If you have a boost gauge try it, and if you don't get boost creep or any spikes then it should be fine. If you see boost issues, throw that cat back on again if you like your motor. You could always get tuned for the open DP or a straight pipe. Turbos generally dislike any sort of backpressure. You could see some significant gains...once again if your internals can handle it.

Also it's gonna be loud as ****-all, especially with no cats. Just watch out for the blues.

Wait how the heck do you know if this guy has a turbo on his car???

[itsnotarex]

Wait how the heck do you know if this guy has a turbo on his car???

He posted this in Forced Induction. Also "downpipe" usually = turbo. I imagine he would have said "header" if he was NA.

However (just to be safe), if your car isn't boosted you'll probably lose power and, at worst, burn a valve. NA motors need some backpressure to run properly. I wouldn't do this unless you're boosted.

EDIT: Also worth mentioning that you'll have uncatalyzed exhaust gases creeping into your cabin. Last I checked that isn't terribly good for your health. Just watching out for a fellow IA member.