The best drivetrain upgrades for a 2006-2007 WRX are the ones that sharpen shift and clutch feel without hurting daily driveability. Clutch delay valve deletes — Perrin and OVERTAKE both make them for this car — remove the factory delay for a more direct pedal. Pair them with upgraded gearbox and shifter bushings, like Whiteline's positive shift kit, plus driveshaft carrier bushings to take the slop out of the whole system. These small parts make the biggest difference per dollar; save clutch kits and flywheels for when you are making more power.
The drivetrain is everything between the engine and the wheels: clutch, flywheel, transmission, driveshaft, and differentials. On a 2006-2007 WRX — most use the 5-speed — the factory rubber bushings in the shifter, gearbox mounts, and driveshaft carrier soften with age and heat, adding vagueness to every shift. Polyurethane and metal replacements tighten the whole system back up. A weighted shift knob is a simple upgrade that many drivers notice immediately. When shopping, confirm fitment for your transmission and model year on each listing.
Popular brands in this collection include Whiteline, Mishimoto, Perrin, and OVERTAKE. Browse related upgrades in our Clutch, Shifters and Bushings, and Shift Knobs collections. Featured picks: the Perrin Clutch Delay Valve Delete and the Whiteline Gearbox Positive Shift Kit. Planning a full clutch job? Read Performance Clutches: Choosing the Right Upgrade for Your WRX STI.
What does a clutch delay valve delete actually do?
The factory valve slows clutch fluid flow to soften engagement. Removing it restores a direct, predictable pedal feel that most enthusiast drivers prefer.
Are bushing upgrades noticeable on a daily driver?
Yes — worn rubber shifter and gearbox bushings are why many 2006-2007 WRX cars feel vague. Upgraded bushings tighten shift feel without adding harshness for daily driving.
Do I need a tune after drivetrain mods?
Most bushings, shift linkage, and clutch hydraulic upgrades need no tune at all. Clutch kits and flywheels change how the car drives but do not require ECU tuning by themselves.
When should I replace the clutch itself?
When it slips under load, the engagement point moves to the top of pedal travel, or you are planning a power increase beyond the stock clutch's capacity.