Just a quick update on filters.. I am in the process of waiting for mine to arrive now, but I believe the exact correct part number is RU-4450. Only $30.72.
http://www.ajusa.com/cgi-bin/knfilters/details?part_num=RU-4450
There's the link. The people that are paying 55 dollars or such for them are either getting them from local stores, or they're buying the kind that has the inverse conical top.. The one with the intake hole in the top of the filter too. Since I haven't seen anything that is proof of more power with a reverse conical intake, I'm going to save my 25 bucks and just get this one.

It's a 5" long intake. As far as I know, myndfi3ld's fits, you can also get the 7" long intake too apparently, which is # RU-3610.