Focus RS Big Throttle Body KitLooking to get a little more out of your Focus RS? This kit allows you to run a larger 63mm Ford throttle body commonly used on the 2. 3 Ecoboost Mustang, vs the factory 57mm unit found on the Focus ST and RS. Throttle body is optional if you wish to source your own from the 2016 2017 Ecoboost Mustang. Benefits: Improved throttle response Increased horsepower and torque Easy factory like install No tuning required, but recommended 63mm measured