Assuming the removal of the cat from the exhaust would create a somewhat more free flowing exhaust, could it be compared to if the cat was left in and the OEM mufflers were replaced with aftermarket slip-on's ? I'm trying to find out if the cat removal on my 2012 RK would have any affect on the system as the ECM is still working with the factory map.

 

I don't think you'll notice any difference

 

the main reason that most people remove the cat is to eliminate heat on the rider and passenger's right side. catalytic converters generate high temperature to burn exhaust gases. you will get a slightly louder sound from your stock exhaust and a noticeable reduction in heat...the after market slip on's will make more noise. might try removing the cat first and see how you like the sound, and add after market mufflers if need be.

 

The cat was removed by the 1st owner, with everything else stock. I was hoping the cat removal would have aided in a free flowing exhaust as I'm happy with the OEM mufflers, but want to add an aftermarket air cleaner. As for the heat, it seems to be cooler than the '09 Ultra I used to ride, so if nothing else, and improvement in riding comfort.

 

The design of the cat chamber can, on a few, create a bit of a reversion problem resulting in some restriction of air flow. This potential restriction in air flow may also play games with the O2 sensors as well depending on the care taken when the cat was removed.

Yes, there are many anecdotal stories and almost all those rely on seat-of-pants testing methods to disspell any problems with grinding out the cat.

And yes, I've been in the dyno room and watched data runs on a bike that had its cat ground out only to witness some funny data coming from its O2 sensors.

Over time, I suspect both the sensors and map will likely degrade and provide more business for dyno shops.