According to SPEC, the clutch kit will fit a 2015 Focus ST, and its torque limits should be able to handle the power your ST is putting down. However, I would strongly advise you to get an aftermarket flywheel. Dual-mass flywheels really can hold a ton of power or handle extremely hard launches and aggressive driving. Pulling your transmission off your engine isn't much fun, and needing to do it twice because the flywheel couldn't handle the power would be less fun.