I believe in calling the kettle black, you people better be ware , buying anything from robbmac performance. I bought a set of heads from him, which I`m happy with, after changing a few things. But the rockers he sent me to go w/ those heads, weren't ever machined for retainer clearance , from the factory. He wouldn`t stand behind them, and told me so on the phone. If he don`t like what I`m saying, he can kiss my white . flat Irish *** ! this may save some of you some trouble in the future.