This is a Procharger Race Surge/Bypass Valve AV004A-2 .
It is designed to support up to 2200hp+ supercharger applications.
This unit dumps to atmosphere so it can be quite loud under high boost.
This is the best designed and most well built unit I have ever seen!
For those that dont know:
When you are under boost and have your foot on the throttle there is pressure flowing into your engine going past the butterfly valves in your carb (if NA)... Then if you took your foot off the gas the butterfly valves close and the boost has no where to go ( Surge )... This valve detects ( by vacuum) when your butterfly valves close and dumps the trapped boost out to atmosphere Thus preventing damage to your carb, intercooler, and supercharger ( or turbo )
Bought this from :
