Originally Posted by Sharkey

no i wasnt hearing the recirc valve, it was the distinct noice of a turbo ecotec in boost. ive beuilt a couple of 2.2l ecotecs with turbos, even with a restrictive intake to quiet the turbo, you get a very distinct noise when its in boost. hard to describe.

the wastegate it to controll peak boost pressure, all turbocharged cars have a wastegate, unless its a VNT (variable nozzle turbo), wich is quite a complex turbo and hard to explain how it works.