Loudvalves 3" Boost Activated Exhaust Cutout/Dump stainless steel bypass valve Fully Automatic Operation, No switches, no electric motors to burn up, just hook up a boost reference line to the valve Opens at about 6psi of boost (can be opened at higher boost if desired with boost controller) Cast Stainless Steel 304 Body will ensure years of troublefree use 3" inlet and outlet.