Rain has no ill affect on CAI....I've have 40k on my injen cai.....Driven through the worst storms car washes....no problems...I wouldn't drive through large puddles...but who would?...

 

I just bought a K&N, and I'm tempted to put the stock airbox back on.

I love the way the stillen sounds, but I am curious to see if the car is quicker with the stock/k&N setup.

 

When it rains, puddles are formed and that's why you shouldn't drive a CAI in the rain. Last thing you want to do is drive your car over any puddle. If it's raining really hard and you're 100% sure you can avoid going over puddles, then da45king is abolutely right about the rain having no ill affect on a CAI. The CAI doesn't sit an inch from the ground so technical you can go over puddles, but if you submerge your filter in water you can say bye bye to your engine.