Synapse SB Nissan GT-R - without BOV - only accessories DV Series Synchronic BOV For Nissan GT-R, only the accessories - without BOV! Patented technology allows the drive of extremely high boost pressures. The SB uses a valve instead of a piston as usual. The valve is opened to open and allows air to flow off, while a piston valve is either in danger of being "pressurized" by air or swirling the air (in pullmode) and thus inefficiently venting. Synapse BOV/s are currently the fastest available on the market.