They've got a new head out for the 66/80cc engines. It cool lookin'. Piston bikes is sellin' it for 69.99USD. Its called the Maniac Mechanic Gen 2 Head. Its a definite improvement over any stock head. The way the sleaves are angle toward the center, that'll help cool it down alot better. Heres the link:
Manic Mechanic Gen II Head
Manic Mechanic Gen II Head