<p>If you are looking for maximum performance then a compressor bypass valve or CBV upgrade is essential. This piston design re-circulation valve is made of billet aluminum and is a direct replacement for the original valve. The stock CBV is designed for stock boost levels so its lifespan and capacity to hold pressure can be significantly shortened once you have increased the boost with a ECU upgrade. </p> <p>The stock K04 turbocharger comes from the factory with a rubber diaphragm and spring type design valve which can crack or become brittle from overuse and age, by installed our piston style valve you not only increase the durability but it also has an enlarged re-circulation area to accommodate the increase boost/air flow from a tuned engine to minimize boost spike.</p>