We here at Houston (HFXA) already did tests with all diff CAI's ( see more in HFXA meets), it is up to you to determent which is best for you.
-Every car, every driver is a little diff. with each other so, by upgrading only an CAI, you'd only see diff in nano of a sec. or perhaps don't see/feel any thing at all accept you HEAR it loud, and would be LOUDER if you replace the resonator with the Z-tupe.
-So taking your OWN car out to race track to get before and after number would be best result for each individual. But if you don't think a nano of an sec. is important then just make your wife happy and put the rasonator back in the car. IMO, on everyday drivings or just on ordinary streets, I don't see a nano sec. is a huge factor. It just all depends on how DARE you take yourself and the car to the limits. but other ppl would called it stupidity.
*Note 1: Remeber, for street cars. Louder not necessary faster.
*Note2: You probably know all about this because 1 of us here in Houston has/had the "Sinciti Mod".
*Note3: A NANO SEC. IS VERY IMPORTANT AT THE RACE OR ANY COMPITITION EVENTS, IT CAN DETERMENT A WIN LOOSE SITUATION, regardless what ever you do with your car, regardless what ever weather cond is. If you get ET 14.99sec. You automatically becomes the fastest of the V6 catergory. (this applies for us ORG here only).