I pulled up this great article on "KFX/Z-400 Exhaust Shootout" from Dirt Wheels March 2003 - http://www.ctracing.com/ltz400%20pip...t%20mag%20.htm

I am deciding between the HMF and the CT pipes. The HMF cranks out .7HP more at 4000rpms and the CT is .8HP more at peak rpm. The HMF package (pipe, header, jet and filter) is about a little less than $100 than the CT package - I've done my own research. My question is: are these "minute" differences actually felt on the bike? I'm a newbie, will it make much of a difference? Thanks for you opinions.

 

whatever exhaust you decide, you will notice a big difference in power