Is there such a thing as a Blow-off valve for a supercharger. Anybody know why or why not? Also is there a valve or device that would release boost pressure when just driving normally around town but close and apply boost when the car is given a certain about of gas. I am looking to put a Renntch pulley kit on my Coupe but wanted to see if I could keep boost levels down when driving normally for reliablilty issues. Thanks for any ideas or help.