ImprezaWRX

I have recently purchased a Forge Dump valve (vta) for my 1994 WRX.
But I am experiencing a lot of "Chatter" and little "pssssttt"
I have searched certain threads on this and the overwhelming response was the spring.

I contacted Forge and they despatched a weaker spring the original being blue and the replacement yellow, However this made no difference to the sound at all, Forge then sent a replacement valve out as a precaution just in case there was a fault with the original, once again no difference.

My original re-circ valve did make a distinct "whooosh" that was more than audible from the hks cone.

Can anyone suggest why/what could cause chattering, as the valve almost certainly must be performing?

Thanks to the staff at Forge Motorsport for their Help and speedy response in posting springs and unconditionally sending another Valve as a precaution to a fault.. Respect.

Please any help will be more than appreciated

Mick