VTT - Billet Vacuum Relief ValveVTT Billet Vacuum relief valve allows you to dial in your crankcase vacuum to the precise level you choose. No more wondering if you have too much or too little vacuum in your crankcase. With this valve simply add or remove shims to get the desired vacuum level. The valve is designed with 10ORB threads to be a DIRECT screw int to any of our modular PCV solutions and our Modular CNC Valve covers. Simply screw into an open port, and you can seal your