All you guy's that own the z20net engine should check the folowing part for manufacterers default which would not be cvered under warenty as you don't get one with the turbo nor would be be ble to claim on it once you strip the valve off to check.

Upon the recirculation valve which is bolted to the turbo once removed it consist's of the folowing parts, outer casing, spring 8-12psi, diaphram & casing, gasget.
If you look at the turbo aperature with the recirc valve off you will notice an inner hole where the boost air enters the recirc valve, a resessed grove and the outer sealin ring. If you place a flat object accross the aperature it is flat ,so by having the gasket you don't create an air tight seal as you are only compressing the gasget not 100% sealing the diaphram casing to the turbo.
If you look upon the diaphram casing (the one with holes around it in plastic) their is a recess in the end of it which is where a o ring should be seated to seal against the turbo recirc hole and the gasket as a leveling seal. I have inspected 4 gt20's 2 being my own and one off my mates signum 2.0t and aother off an edition 100 like mine only one had this fitted.
If you want to get one the only place is from forge motor sport the guy's with the dump valve kit will have noticed the o -ring in the centre of the blanking plate but if they look at their recirc valve they should have one in their also.

If you look at the how 2 on fitting dump valve you will see the recirc in question.