i had my eclipse for over 2 1/2 years w/ my AEM CAI where the filter is positioned at the same height as the bottom of my front bumper. I've driven through 6" puddles, heavy as can be rain at 60+ mph and never had a problem what so ever. if you are concerned about this problem there are 2 other options.
bypass valve. this is a valve that AEM and i'm srue a few other people sell that attaches to the CAI at a different location so that if your intake does get compltetly submerged it will not hydrolock on you HOWEVER the drawback of this product is that you will be basically bypassing the point of a Cold Air intake b/c you will be now pulling air in from the valve whereever it may be positioned.
If you live in an area w/ heavy rain and deep puddles on a reg basis, i'd go w/ a Short Ram Air however w/ the 420a engine you won't see much different either way. i'd say get a ebay short ram intake.