I really want to get a slip-on pipe, jet kit and k&n with holes in the airbox lid for my 1999 400ex. I was looking at the pro circuit t4, WB e-series and r4 and the yoshimura standard slip-on. I think I would be satisfied with the power gains from each pipe, but which pipe is quietest? How much louder is the quietest pipe over stock? Please I need an honest answer, not just people who favor one pipe over the other because the own it.
Thanks
Dave