OEM vs STK Dual Racing Valve Spring Kit – Nissan A14/A15
Introduction Valve springs are one of the most critical components in any engine, directly affecting airflow, RPM capability, and long-term reliability. On Nissan’s classic A-series engines — the A14 and A15 — the factory (OEM) valve springs were designed for low to moderate RPM daily driving. They were never intended for high-performance use. As soon […]
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