Polaris 90 hop-up question?

[bmurray]

My buddy is in the process of rebuilding hi son's 90. He purchased a Wiseco piston kit, and was wondering if anyone has shaved the head down on one of the quads. I think I can mill off about 0.5mm or .020". Has anyone done this? Any other performance hop-ups we can do outside of purcahsing a pipe and K&N? What it the best pipe for this bike also? Thanks

[bigdaddy]

We are running a Hetrick pipe on my boys Polaris 90 and It works great. I would call them and tell them what you are looking for and they can set you up. Personally I would stay away from a K&N filter if you value your motor. I would buy a perfofmance head instead of milling the stock head.