GFB is no stranger to dual port BOVs. In fact, GFB pioneered the design in 1999, following up with the patented venting bias adjustment system in 2001. This technology is not just a gimmick – it’s the key to getting a blow-off sound without the issues (unlike other valves), and is exclusive to GFB. Unlike factory bypass valves, or other brand valves that require different springs for different boost levels, a GFB valve CANNOT be forced open by high boost! The balanced piston design in a GFB valve uses boost pressure on either side to cancel out the forces, it doesn’t matter how much boost you run.