I called aFe just before I left work tonight. They don't make a CAI for the 4.6. I've left a message for the technical guys to see if one from the 4.4 can be retro-fitted on the 4.6. If this is the case, then this leaves GruppeM and Dinan.

There's also a lot of great reviews coming from Streamline Engineering replacement filters from over on the e46 M3 boards. I've been trying to find someone to ask if they make a replacement filter for the X5's.

Rumor has it they make the K&N and stock filters look sick (in a bad way...).