Sunday, April 15, 2007 - 05:55 pm, by: Brian Timms(Turbo_brian)
To have a BOV completely legal, it must be plumbed back, or the venting gas must pass through a catalyst style converter.
The reason behind this from an EPA perspective is that the BOV is venting gas that has passed through a mechanical device, and is venting gas at the front of the car.
Under Australian Standards, no vehicle is allowed to vent a mechanically discharged gas BEFORE the last openable window on the vehicle (so for a 2 door sports coupe, the gases from a BOV/exhaust, etc can vent from behind the front door, but for a 4 door, it must be from no further forward than the end of the rear passenger door).
It's not the actual fact the BOV is venting dangerous gases, but that it is "potentially" venting a "possible" dangerous gas into an area that could be picked up by your car's venting system.
If your BOV is 100% plumbed back (it pushes the vented pressure gas back into the intake side of the turbocharger), then it is 100% legal because there is no possible discharge of gas.
The other way the EPA can get you for a BOV is for the extreamly noisey valves, and they will fine you for noise pollution.
Also, it should be noted that due to the reasons behind BOV legality, it is not factually possible to get an engineer's certificate to cover an aftermarket valve, unless it is 100% non-adjustable/changable plumbed back.