15. With the backing plate still mounted to the throttle body, Jim took the assembly to the porting/polishing station. In this process he cleans up the backing plate and throttle body ports and makes sure their ports match up perfectly by cleaning up any drops or steps at the mating surfaces. He’ll also clean up the casting imperfections in the throttle body left by the casting process. It’s a three-step process that involves light grinding, sanding, and then polishing. Fuel Moto offers its throttle body porting service for $169.