If you ride alot in cold weather, keep the cat so you won't have to buy thermals!! It's like your motor has asthma with the cat in the pipe, I just don't buy the theory that it isn't restrictive after cutting mine out and seeing it for myself!!!

 

Oh my god yes....it made a huge diff in removing the heat, and the tone changed to that of a slip on pipe.

 

The cat elimination made a startling difference in performance, at least as much as replacing my stock air cleaner with a stage 2 Big Sucker.

And yes, it is more restrictive than the North Korean Gov't.

 

I put 1000 miles on my 11 RK completely stock, even with the windshield off I could feel heat on my right leg all the time, even on the freeway. Next I put on Bassani 4" megaphones, sound was great but the heat was the same. About 1500 miles later I got a no cat 09 head pipe and a FM mapped PCV and a SE air kit. Now without the windshield I cant feel the heat unless I'm going slow in traffic, big improvement. Only down side for me anyway is with out the cat the megaphones are a lot louder, sometimes on long rides they get to be a little to loud. I don't know how much the cat restricts the air flow, but they make a big deference in the sound and the heat on the right side.