Straight pipes no muffler

[ommkevin]

does any 1 know if it hurts the engine when you run straight pipes my friend said that you need back pressure for the engine to run right will straight pipes gain power will you need to re jet if so what to i have a stock 400 EX no air box lid and brand new stock air filter

[FoxRacing81]

Don't do it. Engine damage will occur. And its waaaay too loud that way.

I have heard mix-things about needing back pressure....but running just a header will definatly cause engine damage.

-Justin

[brian-250]

Straight pipes on a 400ex will burn the valves out, some people say ot will not hurt it but i can tell you firsy hand it will.;)

[trx400exxracer]

I saw somebody with one and it looked like he had disk and a cap on the end of the pipe it looked like it was off of a fmf megamax or DG xcellerator and the whole pipe was chrome it looked trick but it was probably just as loud as my hmf