The R-Type BOV is good for those who have replaced their stock turbos with larger ones and are running more boost pressure. GReddy offers the R-Type BOV, which should only be used for high-output race engines in excess of 500hp. A blow off valve relieves pressure that builds up in the intake system when the throttle is closed quickly (between shifts, for example). This valve is an extremely important part of any turbo system, and allows quick boost response and greatly increases the life of a turbocharger. Original equipment valves function well, however they tend to be unreliable at higher boost levels.