I just installed an fmf Q series pipe on my 03 crf 450. The sound level is reduced, and the noise does not carry as far.The power is smoother than stock on the bottom and close to stock top and mid. This pipe would be an excellent choice for offroad. I think the stock pipe is better for motocross, depending on your skill level. In low traction ,muddy off camber, rooty woods of ohio the smooth bottom end gives max traction!