Race Throttle Assembly. RFX Race Series Throttle Assemblies are O.E.M. replica throttle assemblies and feature a die-cast throttle housing and plastic throttle tube. Complete with rubber boot, where necessary, they are an ideal cost effective replacement for any throttle. Features: High-quality O.E.M. replica throttle assemblies, designed for reliability and affordability. Featuring a durable die-cast throttle housing and a robust plastic throttle tube. Each assembly comes complete with a rubber boot (where applicable).