HKS EJ25 SUH 409 Turbo Exhaust Manifold

HKS Stainless Steel Equal Length Exhaust Manifold — Subaru EJ25 (14019-AF002)

The equal length header, and the reason people buy it is as much about how the car sounds as how it makes power. The factory unequal length design is what gives an EJ its distinctive rumble. Going to equal length primaries changes that character entirely — a cleaner, more conventional note — and it does it while retaining the stock oil pan layout, which is what makes this a bolt-on rather than a subframe-out job.

The performance side is straightforward: equalizing primary length reduces exhaust gas pressure and delivers smoother flow to the turbine. Throttle response is noticeably more sensitive and easier to control, spool improves, and both horsepower and torque come up.

Weight is the underrated spec. 5.2 kg versus 9.5 kg for the OEM manifold — nearly 10 lbs off the front of a nose-heavy car, and it's all ahead of the axle line.

Specs: SUH409 stainless steel construction, 42.7mm primary diameter, 2.0mm wall thickness, equal length primaries. Two-bolt up-pipe flange that accepts the stock up-pipe or aftermarket units with a stock two-bolt flange. Installation hardware included.

Fitment: Subaru EJ25 — 04-14 WRX STI, 15-21 STI. Retains stock oil pan position.

Not CARB legal. Cannot ship to California.