I'm not going to argue with the experts. I run my CAI in the rain and I was in on the hydro lock discussion that's why I said flooded intersection rather than rain. Nor am I comparing a NW duel system with the Code 3 foam job. However, if cost is an issue.. I would like to defend the green foam though. I have no desire to blow up my 15k engine either. I've run a lot of K&N filters in my day. Hold them up to the light, then hold some green foam up to the light. There are bigger holes in the K&N. Since I service my foam frequently I can see that no dirt is getting through to the other side. I ran green foam on my Norton and got the same results. The key is cleaning it often.