The gnarly can be tractored, but is also effective throughout the entire RPM range, I also have a 11oz flywheel weight.
I have the Fatty on my YZ250, it provides better power than stock everywhere
the gnarly is also made of thicker steel than the fatty so it is tough
I hit a tree a couple of weeks ago, broke one of my left toes, there is tree sap on the pipe but no dent. I thought for sure my new pipe was gonna be toast.