Gary,
The blowoff valves are typically used on road race cars or small engines with turbo's. The blowoff valve would release pressure and is usually routed back to the front of the mass air meter on EFI cars so that the computer sees a closed loop of air for proper fuel management. This aides in on/off throttle and reduces heat and lag in small engines.
A mechanical supercharger does not need it, you would also need about 4 of them to pass the volume of air in your MONSTER motor if you wanted to use them.
Perry.
