Here's the sticky for doing the triples ....
Link Removed
The only variable is the air temp sensor filter recomended on the sticky thread, you won't need it if you plan to cut a hole in the 1st filter and mount it there. If you go that route, extending the wire harness will be required.
I ran underseat K&N for awhile with my Corbin and there was plenty of room between the intake and the seat, I didn't notice any problem prior to going with the triples.
In fact I have a theory that the stock seat air intake limits the top speed of the bike. I just don't see how it can flow at maximum facing backward in a vacuum at 130+mph.