I currently have an Apex'i intake on my TII that was on the car when I bought it. Id like to put a simple K&N cone filter on, but after taking the Apexi unit off the AFM, it doesnt look like a cone filter will just bolt on.

What do I need to install an K&N on the AFM??

 

you need an adapter.
http://www.rx7.com/store/rx7/FCMafAdaptor.html

 

Since your sig says you have an S5, it should be pretty obvious from looking at the AFM inlet that you just need a filter with a 2.5" ID neck. No adaptor required.

 

Hmm, guess Im blind. When I took it apart, it didnt look like there was enough material to clamp on to.