If its a diaphram dump valve then ive only known them to work on cosworths and renault 5 turbos etc for some reason, i originally had one on my s12 when i bought the car and it idled like shit, it was coz the spring was too weak, ya need a piston type m8.
Try an xs power single or twin trumpet like myself, shaun and pukka use, plenty of whoosh whoosh with them
