Porting was different between 01 & 02...That's why PC spent so much time developing the pipe for the 02s. Big difference!! PC did the development -FMF did not make an 02 specific pipe, DOMA did. IF you get a PC pipe that is not the 02 version, it will make the 02 bike horrible (trust this one-the bike will run like a 125, but with 48hp when it comes on the pipe)....#1 pipe 02- PC, #2 Doma, #3 SST, #4Stock, rest were below that. Based on dyno & seat of the pants. This is for the 2002 250 SX only-not true with the EXC or MXC which were previous generation motors.