I'd agree with you if you are buying a CAI that "doesn't require a tune" because all you did was change the look in that case. No increase in the ability of the engine to breath because you didn't change anything. You are getting the stock air flow so you don't get any codes off it and you don't notice a performance difference because nothing changed from stock. Like my wife (who admits she knows nothing about cars) said "so doing that is just to make it look pretty then"

BUT, if you buy an intake that does increase the flow to the engine, and requires a tune because of it, then you will feel the difference and it is more than a cosmetic upgrade. Your car can't run properly on the stock tune because it no longer flows like the stock set up; if you don't change the tune to compensate then you will get an engine code.

When my car was N/A and also when I was using the Zex kit, I had the C&L intake. There was a definite difference in the car the first time I drove it after installing the C&L and the updated tune. I don't know what the "best" CAI is out there since that is all relative and I only have experience (as will most of us) with one version. So to the OP, make sure you get a CAI and tuner package and not just a "pretty looking engine bay item" and you will be much happier.