For Speed Density Applications that don't have a MAF or VAM UNLESS it's a blow through MAF and the BOV is mounted pre-MAF.

Made from billet aluminum, this atmospheric blow off valve dumps the boost air to atmosphere through the horn shaped outlet creating a VERY loud "Whoosh" sound when the throttle is lifted.
Because this valve is a single piston design, it can created some driveability issues if spring preload is not set properly which allows the valve to open at idle or part throttle, creating a vacuum leak. For this reason, this valve works best with speed density ECU systems that don't use an air meter (VAM or MAF). This includes standalone ecu's like the PiMP,/PiMPx/PiMPxs, Megasquirt, Haltech, F.A.S.T, etc. Designed to be attached to the 1.25" flange included with the blow off valve. We can weld this flange to any of our on all of our intercooler kits when ordered together. 

6mm ID hose fits snug but certainly needs clamped on. 4mm ID hose is very tight/stretches over and would not need a clamp. So measure the port you plan to connect it to on the vacuum tree or turbo outlet and measure ports you may also connect to the same hose (like a boost controller) to determine which size you'd rather use so you don't have to adapt to different sizes. 

Includes:
Blow off valve, steel and aluminum mounting flanges, preload adjustment spacers, installation tool.

Installation:
Vacuum port connects to a source that sees both vacuum and boost under each condition which means the signal needs to come from after the throttle body such as connecting directly to the vacuum tree.