Turbosmart's springs are designed to work with our Plumb Back, Dual Port and Supersonic blow off valves. They offer a wide range of spring rates to suit your driving style and application. Turbosmart's springs are made from high-quality materials and are designed to maintain the peak performance of your blow off valve under the most extreme conditions. Choose from our selection of Turbosmart springs to get the perfect fit for your car and the best performance from your blow off valve. Spring - Suits Turbosmart Plumb Back, Dual Port and Supersonic. Vacuum Low - 22inHG, Vacuum High -20 inHG. Suits Turbosmart Plumb Back, Dual Port and Supersonic. Universal