Every time you install a new clutch you should have your existing 2011+ Mustang flywheel resurfaced or buy a brand new one to save time or increase performance. If you are a racer or high performance street driver choose a Ford billet steel flywheel to maintain or increase rotational weight and inertia for easy shifting and hard launches. You can choose a lightweight aluminum 2011+ Mustang flywheel to reduce reciprocating weight, which can soften your launch a little but offers improved acceleration. Many race sanctioning bodies require SFI Mustang flywheels.