[2LZ]

....and cats don't help the heat if you have one in your pipe. They're made to cook. That's the one bad thing about removing the air injector tube without removing your cat along with it. The cat doesn't get as hot without a shot of fresh air when needed under full throttle or heavy load conditions, so it starts to collect gunk after a while.

On the flip-side of that, if you cut out the cat and leave the air injector tube, be ready to replace your muffler packing far sooner than normal because you're tossing a shot of fresh air on your packing instead of the cat, under heavy load conditions. Picture a blow dryer on a charcoal briquet.

The coolest possible exhaust is one with both removed and the port blocked, with a free breathing muffler.