Know Your DCCD Before You Order Parts
The 2015-2017 STI's DCCD uses a combination of mechanical and electronic control for the center differential. Starting with the 2018 model year, Subaru switched to a fully electronic DCCD across every STI, which Subaru says responds quicker and shifts torque more smoothly between the front and rear axles.
That change means DCCD control modules, wiring, and some center diff hardware aren't interchangeable between the two generations. If you're replacing a DCCD component or wiring a standalone controller, confirm which system your STI runs before ordering.
Everything downstream of the diff stayed mechanically similar: the same helical front LSD and Torsen rear diff carried through the whole 2015-2021 run, so most of the aftermarket Subaru STI drivetrain catalog fits either generation.
STI Short Throw Shifters and the 2019+ Gearing Update
Subaru also revised the 6-speed manual's 3rd gear ratio starting with the 2019 model, tightening acceleration through that gear. A STI short throw shifter builds on that by cutting the physical distance between gears, so every shift takes less hand movement and less time regardless of which gearing your STI runs.
Pair it with fresh bushings, a shift stop, and a transmission mount, and the whole shift feel tightens up further. A 2021 STI short shifter bolts in the same way as earlier years since Subaru didn't change the shifter mounting through the run, only the 3rd gear ratio inside the case.
JDMuscle stocks clutches, flywheels, transmission mounts, and short throw shifters for every Subaru STI drivetrain build. Same-day shipping and a price match guarantee back every order.