The fact that I had neglected to remove the main cats on my downpipes has kind of been eating at me since gutting the pre-cats last summer. I decided to cut them out of there today, and holy crap what a difference. I wasn't anticipating such a drastic increase in noise, the thing sounds down right wicked. Luckily I was able to just cut the main cats out, gut them, then weld them back in place without dropping the motor and removing the downpipes all over again.