The world's first ADJUSTABLE NOISE BOV * for street or track conditions at a twist of the wrist! Up until now, making your machine quiet for normal street use, has meant pulling your BOV off and putting it back on when you want that blow-off noise. Not surprisingly, it's been every enthusiasts dream to have a superbly engineered BOV that has absolute maximum throttle response and power in Full Blast mode for the track ... and with a flick of the wrist, runs quiet for the street. Called the StealthFX, this amazing breakthrough is now a reality, the latest in a string of Aussie innovations from Sydney-based hybrid technology experts, GO FAST BITS. It is, as its name implies, the ULTIMATE performance breakthrough in BOV technology, pioneered in the GFB developmental lab. It is ... By utilising a unique air diverting system you control exactly how much air you dump to the atmosphere for noise, or the inlet for silence. By sending the vented air back to the inlet (rather than muffling it), there is no restriction and the valve still operates at maximum efficiency. For cars with sensitive air flow meters, the valve can be tuned to vent just enough air back to the inlet to prevent backfiring whilst giving the loudest possible blow-off noise. No more guessing which valve will work on your car - this one will do it all! Standard Trumpet Driveby Stealth FX with standard trumpet, 15psi boost on a WRX, recorded from the side of the road. This sound is the same as a Mach 1. Standard Trumpet In-car Stealth FX with standard trumpet, 15psi boost on a WRX, recorded from inside the car. This sound is the same as a Mach 1. Standard trumpet free revving Stealth FX with standard trumpet, free revving the engine in neutral. Recorded from in front of the car. The advantages of this system, combined with GFB's other proven features are numerous... Fingertip control over how loud your shifts are! By simply turning the lower ring of the cap, you can adjust how much air is vented to the atmosphere or to the inlet, giving you complete 'noise control' over your shifts! For cars with sensitive air-flow meters, you can dial in the valve to eliminate common problems normally associated with aftermarket valves... and still get a great sound. No tools needed for spring adjustment. Spring adjustment is achieved via the chrome cap on the top of the valve. The unique adjustment mechanism is contained completely within the valve, meaning that the profile remains as low as possible, as the cap does not move up and down when adjusting. Unique piston seals achieve the best possible seal on both ends of the piston. Now, as well as our acetal piston seat, a low friction, lubricant-impregnated polymer piston ring is incorporated. This system is far more reliable than o-rings, which require frequent maintenance and replacement. Tight engine bays are NO problem! The vacuum nipple is free to rotate through 360 degrees to make fitting easier. The Stealth FX is available for: Subaru WRX, Nissan 200SX, Nissan Skyline and Universal Fit.   Hear the Whistling Trumpet for the Stealth FX   Colours available: red, blue, silver or black.