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Hey guys, Great to hear there's some positive feedback on the Stealth FX. As far as the adjustment goes, yeah, there's not a lot of room to play with in the factory location, but on the up-side at least it doesn't require expensive additional hard-pipe adaptors and it also makes it harder to spot! You'll find because of the nature of o-rings, the adjustment is harder to turn if the valve is cold, or if it hasn't been turned in a while. After the first turn, or if the engine bay is warm, it should be relatively easy to adjust. As far as the spring adjustment goes, the firmer it is the shorter the duration of the blow-off, and the more liklihood that you'll get a little low RPM fluttering. The softer the spring, the easier the valve vents and the longer is stays open for. This will reduce the liklihood of low RPM fluttering. Because there's no airflow meter, it doesn't matter to the ECU how soft or hard you have the spring, unlike a car with an AFM. However, generally speaking the best throttle response is had on the firmer side of the adjustment, but if you don't want to hear any flutter at low RPM go softer. There's more info on this topic that might be of interest here: Learn stuff - Turbo lag, how to beat it. Part I - RaceDotCom.com with SuspensionParts.info and here: Learn stuff - Turbo lag, how to beat it. Part II - RaceDotCom.com with SuspensionParts.info I hope this helps! Best regards, GFB Pete

Hi everyone, Pete from GFB here. I hope you don't mind me jumping into this thread and throwing a few more options into the mix. GFB makes a direct bolt-on valve called the Stealth FX (part # 1013) that fits in place of the factory Bosch valve. I'd like to mention that noise aside, there are actually tangible performance benefits to fitting a GFB valve! What? No way! True - a GFB valve will hold unlimited boost, will not wear out or need replacement like the Bosch valve, and can actually help improve throttle response. That said, the great thing about the Stealth FX is it's possible to achieve the following sounds from it: No noise Whoosh (sneeze) Flutter (aka dose, VL, turkey, pidgeon etc etc!) High-pitched whistle (hear a recording here - turn the sound way up!) Or a combination of the above The GFB Stealth FX has two outlets like a dual port, but with a patented feature that allows you to adjust how much air comes out of one or the other (or both), simply by twisting the cap. So in one position you can recirculate all the air like the stock Bosch one to stay quiet, or you can twist the cap to make the noise louder. Also available is a replacement trumpet (part # 5702) that makes a whistling sound at high boost, and a quiet whoosh at low boost. Finally, if you want to, you can adjust the spring pre-load harder to make the turbo flutter - you could even plug up the outlet altogether if want it to really flutter (as has already been suggested)! I should point out that no BOV makes a flutter sound, however restricting the airflow through the BOV or blocking it entirely causes it. The noise actually comes from the turbo, and is the sound of air exiting back through the compressor (easy to imagine it like blowing through the blades of a spinning fan, hence the flutter). The only way to make the flutter louder is to free up the intake, as factory intakes muffle the sound quite a bit. What have been referred to as "dose pipes" by the VL community are typically pod-type filters in place of the factory airbox. Is the flutter detrimental? Not particularly on stock or mildly increased boost levels - the XR6's turbo is relatively un-stressed from the factory. However high boost levels however in combination with flutter can accelerate wear on the turbo bearings. I hope this helps! Best regards, GFB Pete Go Fast Bits www.gfb.com.au

Hi XR64LT, We too prefer not to discuss price etc on any forum and would refer those questions to sales. I'm not sure if we have a recording or WAV file but being adjustable its a little difficult to work out which sound to record anyway. If you like, might be best to conatct me direct on pete@gofatsbits.com and I'll see what I can do. Best regards GFB Pete Go Fast Bits www.gofastbits.com.au

Hi everyone, Hope you don't mind us popping in but someone told us about this thread and we thought we might try to help with some other info. Firstly there was some mention of the fitment of our GFB Stealth model and I'd like to confirm that is in a direct bolt-on configuration, part # 1013. The good news is no mods or changing of pipe required, and you can turn off the sound if you need to. As for the issue of legality and ADR's, we asked our tech guys to comment on this and we've repreinted below, raw Would be great to get your fedback on any of this. Best regards GFB Pete