So I was looking at getting a Two Brothers exhaust for my bike. I don't want just a canister. I take it as a Slip On is just the canister and the Flange On is the Canister and midpipe going down to the HTEV valve flange? I have a 954rr

This is the Exhaust.
http://www.cyclegear.com/spgm.cfm?L1...5-2310406V-B_G

 

Generally speaking, a slip on requires you to cut off a part of the link pipe and slipping the aftermarket pipe over it.. hence the name 'slip on'

Flange on just bolts directly onto the existing OEM pipe mount.