i got this on mine, its ok at the moment, i did have the original standard bailey twin piston dump valve that last about 2 years and then the spring inside snaped, i got a new one as shown above "bailey twin piston EVO" has worked fine since.
i made a tee into the pipe from the inlet to the fuel pressure reg. and the actual valve is mounted on the cozzie intercooler.
the non EVO ones dont have the little screws around the top as pictured.