Swirl polished heads for smoother air flow over the valve.
Back cut to reduce valve weight for higher rpm, higher boost pressure and allow for more aggressive cam profiles without increasing valve spring seat pressures.
Valve stems are micropolished to allow for less oil retention on the stem which creates less drag on the stem to guide for a smoother motion.
Fully nitrated (this includes the 45 which increases valve life and makes a better seal at the valve seat for improved cylinder pressure) also reduces carbon buildup on the backside of the valve.
Intake valves are a modified 21-4n stainless and Exhausts are a modified 23-8n stainless material for high heat capacity while maintaining longevity.
Valve tips are either hardened or have a stelite wafer tip fused so that the tip is within 5 Rockwell C of the rocker or valve tappet for extended life and less wear.
Valve tip lengths. GSC has taken extra time to adjust tip heights on the applications to require less tipping of the valve to maintain proper tip height for proper valve train geometry, and to cut down on install times when setting valve lash.
GSC has also adjusted the keeper grove to properly balance intake and exhaust spring pressures to reduce the use of valve spring shims and maximize performance from GSC spring and retainer kits.
Valves will work with an OEM keeper/lock or when available the GSC upgrade keeper/lock. It's not mandatory but it is suggested that any valve lock not be reused on performance applications do to material grooving.

Performance Tuning

GSC POWER-DIVISION VALVES (INTAKE) 02-14 WRX / 04+ STI

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