On a smaller engine like a 3.8L, a CAI is not going to realize you much of a performance gain. It seems to help most when you've done the work on your engine to actually make use of the "extra air". I'd definitely put on a CAI with a full exhaust (headers, hi flow cats and catback). You would be helping the exhaust do it's job of scavenging more than anything else. Moving on to a truly bored over throttle body and heads/cam/fuel package you would definitely see some benefits from better airflow on the intake side to fill up those newly opened up lungs. Then there is tuning, not the Hypertech kind of boxed tune, but real world tuning with a data logger in your car to adjust timing, shift points, etc.. That's the real key. Once you are there, the CAI would make a lot of sense. Of course, they really aren't "CAI's" anyway since they don't cool the air. More accurately, they are really "ambient air intakes" as most are just drawing in a larger amount of the already hot air in the engine bay area. The heat shields do little to protect the incoming, already hot air from the radiator which is like 3" away and plastic or metal alike will gradually warm up to the ambient temperature of the engine bay anyhow. If you want some better "boost" under load, perhaps a meth injecting kit would suit you well. I swear by mine on the Hemi and they are about the same cost as a CAI. Just my 2 cents.
-Dave

 

Cold air intakes are for ricers in Honda Civics