I'm getting Summit's Performance Headers in a week or two, and planning on putting straight pipes behind them. How long the pipes should be to keep oxygen from going back into the headers?

Another thing, I won't be putting mufflers on. I'll probably get some this summer, but I was wondering if I ran my exhaust without mufflers if it would damage anything.

 

your ears?

 

if you use 1.5" pipes it wont be too loud, but otherwise you will absolutely not be able to drive it for any length of time.
as for the length of pipes, id at least go a few feet past the o2 sensor.
why not go all the way out to the back?
technically, you cant dump exhaust gasses anywhere that is in front of the farthest back opening to the passenger compartment.
which for us, is technically the back bumper.
although i am guessing that you arent concerned because you will not have any cats or mufflers anyway.

post a clip of how loud it is when you are done