I was wondering if rz 350 cylinders would give me more power than stock banshee. Is the porting different enough to give more power. I don't have all the power valve stuff for them but was wondering if I could block off the holes for the valves and run them that way. Tell me what you guys think.

 

Two stroke power valve motors are not designed for higher peak horsepower but instead are designed so that exhaust ports can partially close off at lower RPM and then improve low RPM performance without hurting peak power numbers when power valve is wide open. So for dunes and drags with Banshee you are usually better off to just build your motor for whatever power level and fuel usage you want and then live with less low RPM performance.
The BansheeHQ forum has more Banshee info than you can ever learn and IMO is best Banshee site on web.