Why did you not just order the plugs recommended for your engine ? Loads of information on here about the correct spark plugs to buy or just ask a trader on here that will give you the answer?
This is what most people went for but I'm not sure if flyboy will still be producing them http://www.350z-uk.com/topic/100520-2006-airbox-modvelocity-stack-new-group-buy/
Also I thing cs2000 is experimenting with 3D printed one at the minute.