Wont fit. Kawasaki changed the entire engine in 05. The 05 and up pipe slips over the flange on the cyl. The 03 pipe slips into the cyl. The P/C Works pipe will take away low end and make the power more violent. I tried one on my old 03 and hated it. The FMF Gnarly made a nice improvement in the power delivery on my fiances 07 KX. It gave it more bottom end and smoothed the low to mid transition.