if you do get hmf make sure you get the full system...all the power comes from the header so id get a full system, intake kkit, remove the airbox lid, and rejet the carb

 

All of the power doesnt come from the head pipe. The silencer is what has the restriction. A head pipe will help a little. If you plan on doing future mods, I would get the full pipe. If you only want to pipe it for a little more power and sound you should be fine with the silencer.

 

i shouldn't have said power...all the torque comes from the header