I got hold of a second hand spec-r dump valve recently and have just tried it on my sapphire.

The car is fitted with a twin piston motorsport developements one at the mo but thought I'd try a diaphragm one to see if I prefered the noise.

When the spec-r one is fitted and the car is idling the dump valve leaks a tiny bit of air...
The diaphragm isn't split so I was thinking maybe the spring in it is not heavy duty enough??

Anyone running one of these?

Cheers Paul