I've got a 2000 WR400F and looking to replace my stock pipe. Problem is I can't seem to get a straight answer about what pipes work well and which don't. I've heard the FMF PowerCore IV, Yoshimura, Dr.D., and Big Gun pipes are good and give great power gains. I've also heard the DSP, WhiteBrothers E-series, Pro-Circut, and FMF Q pipes suck. But then again I've also heard the opposite as well. I'm looking for a pipe that'll add good bottom to mid power without loosing any top end power or speed. What have you folks used and what are your opinions?