The thing that sold me on the CAI idea was when I datalogged with the filter in the engine bay. With just a minute idling, the air going into the engine would get up to 150 degrees! Even when cruising, the air temp never got below 120. Since the EEC pulls timing as the air temp increases, that is where the performance can me affected as a result of the hotter air coming in. That is why I moved mine out to the fenderwell. Now it never gets more than 5 degrees above the outside air temp.
It is really easy to build your own with PVC and some FERNCO rubber connectors. Put your money into a new mass air meter.