i think i know what u mean mate. it is a split - r that you have, but by turning the top of it, it will click around 50 times. turning it a certain way will make the piston inside a lot stiffer to move (to retain boost pressure when running a lot of boost i guess?). i've had one in the past, and found that by turning it all the way one way until it stops will either give you a longish dump sound, or give u a 'short and sharp' dumping sound. all depends what way you turn it really and i cant remember myself! there will be a science behind it, but i originally bought mine for the noise

. i was advised to change to a forge 007p for my remap so sold it. sure someone will be able to explain better for me!