I have also noticed how hot the floor and geny compartment get on mine after running it 2.5 hrs. I never ran it longer than that and never had it shut down for high temp. That's a big drop in temp after removal! Did the exhaust get louder after you removed the cat? I had to deflect the hot air coming out of the bottom of mine with thin aluminum sheet because it was blowing on the frame and outer edge wall causing it to get very hot. Now it blows straight down on the ground and reduced the heat on the floor. Your discovery sounds like a big improvement.