Was told by a motorsport regular who drives an Evo that running a set of straight pipes for track days actually helps ([big time] with turbo spool and throttle responsiveness by allowing the engine to breathe better.

Is there any truth to this?

...or better yet, open downpipe! Straight pipes are usually considered piping w/o cats or resonators out the back. But open DP you could consider about just a couple feet of piping from the turbo exhuast and back. Perferably to the fire wall...

Yes! somewhat true... It's still setup dependant.

yep. weight savings too.

but you'll have more than one or two people wanting to kill you, and no matter what set of earplugs you use, you'll still be saying "HUH?" for a long time to come.

This is the same thing as upgrading the exhaust to a turbo back ... less back pressure = better throttle response, quicker spool and more power.

It's loud, but not as loud as one might think. I would suggest running a turndown to keep cabin heat and vibration down.

I dont know if you plan on drag racing or road racing but many tracks have noise regulations that you must abide by. Typically open DP will not meet these regulations.

I had an open DP for a while on the street and it is not that bad. It is sure loud but you get used to it, although it does smell pretty bad from all the fumes. If your race track allows the noise, then I say go for it.

Its cheap, easy, and makes power; it also saves weight.

i run a downpipe and testpipe with a cutout from jegs ($25) built in.... =-)

i wouldn't trade it for anything else....

stock catback for a super quiet ride!

Thanks for all the responses. Looks like this is an option I would like to consider, i.e. cheap and effective track mod.

Two questions (though they may sound silly to some):

1. I have a factory O2 sensor connected to the catback. Assuming I get a turndown that starts from the end of the downpipe, where would I be connecting the factory O2 sensor without throwing a CEL?

2. What's a turndown? From what I'm thinking now, it sounds like I could (maybe) just get a foot or two of pipe, and bend it 45 deg to point downwards, and connect that to the end of the downpipe.

For all the comments I get about blowing fireballs out the tail I don't think I want all that flying about under my car with me just above it.

I have similar concerns, and was also contemplating running it out the side or out the back

i run a straight pipe from the turbo all the way out the back of the back bumper, no cat, resonator, muffler. its pretty damn loud... but i dont get black flaged at our track for noise issues.

How did you avoid the CEL issue caused by the rear O2 sensor on the catback?

Search for the sparkplug "anti-fowler" in the EVO engine, turbo and drivetrain forum. Basically its a little pipe that moves your O2 sensor away from the direct flow of the exhaust and avoids a CEL.