I think they used K1 stuff on the internals. The 09 heads are a heck of a bargain at $600/pair complete. They even come with 16 iridium plugs. Those alone are worth over a $100! I know those flow 300 cfm @600. Porting shows the normal improvements in flow as well. Arrington and another company are in the production phase of rockers that will allow the use of solid rollers.