[ujiro]

I think you should be ok with the stock piston head. Although, a good idea maybe if you wanted to change it would be to get the MASK one, or just one that provides proper air seal, and then put a sorbo pad on it. Higher rate of fire setups will cause undue stress on the mechbox. Sorbo helps soften that.

check out airsoftparts.ca. Jugglez carries the MASK piston heads