It is not a bad mod by any means. i personally like the example from:
http://www.gmhightechperformance.com...ons/index.html
it gives you exact pictures of what you need to do/cut(even with more than just your free ram air mod)
and unless your a crazy madman running into 2 feet of water, you will be fine
Rain here in nebraska doesn't get my filter wet at all.

 

I did all the free mods and dropped .5 off my 1/4 time.

 

I did the free mods and i felt a decent gain and seen it on the time clocks about .4 myself so i say deffintly worth doing.

 

You do have to be careful in any large puddles or deep water with this mod. Water doesn't have to splash over your hood to be sucked into your motor after doing this mod. I got caught in a flash flood in my TA which is lowered about 1 inch max and enough water came up between the air dam and the radiator to choke out the motor and kill it. Apparantly no water got past the K&N filter into the engine but it scared the crap out of me to say the least. There were pine needles and crap(that was floating in the water)all up the radiator and stuck around the bottom of the filter. It looked like the water came up from the bottom and then poured out the front of the airbox. I'm glad I didn't have the front sealed off at this point in time as there wouldn't have been anywhere for the water to go except into the engine.