Originally Posted by dave_y
do dump valves have any performance gains at all?
my friend keeps telling me to put one on my car but im put off by the noise.
he seems to think it will reduce lag and preserve the turbo...?
That's just the bullshit that the MaxPower pricks beleive and quote at you in the pub. On a monster car with huge turbo and loads of boost yes on a road car with a turbo smaller than T4 or less than 30psi there is no need for one whatso ever.
I had the twin piston Bailey on mine and although it was hugely better than the diaphragm unit I was using it was still a huge improvement when it was binned. I will not be fitting one unless I absolutely have to.