I do have a solution for that, just didn't have time to get it put back on. Again, this was just the proof of concept and I will be finishing it up and share the final configuration in a couple weeks.

My plan is to remove the exhaust and make notches on the back side so it can be pryed open and gutted, this should prevent any fitment issues when I go to weld it back up. Btw, just ordered some .030 flux wire and 14"gloves and once I get the hang of it will do this mod and report back the results.. similar to the other bikes I'm assuming it should net 1-2hp maybe but be a signification seat of the pants change

I did the same thing that IA Grvlrnr did. I cut the cat right out and used 11/4" flexible exhaust pipe that I got on e-bay and stainless clamps. I did use some exhaust sealant on the joints. I removed the nut on the cat and welded it back on the flexible pipe so the heat shield hides it pretty good. Now it is a lot more snappier and revs quicker but it is a lot louder. So now I am working on a baffle that slides into the end of the muffler. Doesn't sound very good anymore but is quiet.

Hmm, figured it would be slightly louder, but alot louder, hope its not crazy loud.. if its the same as the Stonemen exhaust in my son's Brozz, then im fine with that, louder than that and not sure if its worth it

When I decatted my Brozz , it may have been a little louder, but it was still very quiet till I did the muffler. I decatted my Hawk, and it did get some louder, but still not as loud as the aftermarket, even with the spark arrestor/ baffle removed it's not very loud. That being said the cat removal made a noticable improvement in performance on the Hawk, and if it improved performance on the Brozz ,it was more of thinking it may have, but kinda hard to tell, as opposed to the definite improvement on the Hawk . It's probably good to get rid of them, but I think on the bikes that have the larger chamber ("bulge ") to allow the bigger around cat, the cat is not very restricted. These cats remind me of an open ended canister,packed with coffee straws, so it's natural that a cat as big around as a tomato paste can ( like the Hawk) will flow far less than a cat as big around as a Dogfood can( like the cats in the Brozz, and other bikes with the chamber for the larger cat. I have a feeling that I could have left the cat in the Brozz, and just opened the muffler, and still flowed just as free as it did with the cat removed, and the muffler open. On the Hawk, and bikes that have the cat that's basically the same diameter as the head pipe, it would probably just be a waste to replace, or modify the muffler with the cat still intact.

Update: removed the exhaust, cut it open with a |__| shaped cut to the back-side and then pryed up and jimmied the cat out. I then banged back to shape and had a friend give me a hand to weld it back up. I am a total newb to welding so didn't want to experiment on it.
He had to do a couple bridge type welds and commented that it was penetrating to the backside easily. I then used an angle grinder to clean it up and re-installed to the bike.
After install, it was quite loud like it had a leak at the head so i tighthened up further and it was perfect. I still have to test out on a ride but as far as sound goes, its only slighty louder, maybe 20% and not excessive. I'm happy as it was a long time to-do item on my list

Took a test ride today and can confirm a decent increase in power, not huge, but noticeable. I can hit higher speeds quicker than before which is nice and knowing that its not bottled up anymore and equivalent to any good aftermarket pipe without any added cost is a bonus

Good stuff. I need to get some SS flux core wire and knock this out too

You won't be disappointed! On a much longer ride today the de-cat has truly earned its place as an awesome mod, there is a sweet midrange and top end bump that wasn't there before.. i was actually even able to pass a car on a 55mph 2-lane highway up a mountainside hill, that would have been a real challenge before.. and sustain 65mph on speedo (60 mph corrected).. good times!