dose anybody have these upgrades and how do they perform

 

I have the HPD air box mod and it works great. Better throttle response and more "snap"

 

I ran a web cam and a ported head, hi comp piston, pipe, w/ stock box and k&n filter. you will see gains for the most part, but for the cam the biggest gain is the piston, porting, and valve work. you have to make the motor breath with the cam, otherwise its a waste of money. we have the cam in a stock motor, w/ k&n and pipe right now - wouldn't say it really made the difference.