I tried a few options when I first got the car 3 years ago, including 3 different pod setups, one with heat shield etc.
I then read a number of related articles, including an interesting one on Autocar or was it Autosport which said various test they had conducted showed a well designed standard airbox system was best all round. Interestingly it also said that if you must fit a pod type go for the Motor World "Race-X" as it was the best on test! (And £25!)
So I did the following mod to the standard airbox..and no, rain doesn't get in and mess things up, even carwashes don't faze it, loads of air through the additional 4" intake, and it's very direct so no lag. Replacement panel filter (dry) is Nismo.
Works for me and cost about £20 and took all of 2 hours including thinking time.
In conjunction with the decat it sounds awesome and goes link stink from standstill! Does appear to have lost out a little at the top end though, not that that concerns me, the drive's not long enough on our house!
Aitch