I have and HKS power flow induction kit which I notice gives a dump valve whoosh on changing gear (on standard dump Valve). Is this normal and is there much benefit in an uprated dump valve and which ones would you recommend?

 

mine used to do that too, but i have a better d/v now.

 

Which dump valve have you got?

 

they do it with all d/v AFAIk, as the dump valve returns air to the inlet pipe just before the turbo, and as the throttle is closed, there is only one way for the air to go, through the filter i think, hence the woosh noise.