FWI question

Here's the specific one I'm looking at buying.
http://www.wbodystore.com/grandprix/product_info.php?cPath=5&products_id=63

With the fenderwell intake, should I be worried about rain or anything?

Absolutely. That area gets saturated with water coming in from the front end especially from the headlamp. Depending on how much rain you get in your area I'd consider some water protection (shield) after it is installed.