Tony,
while the MILs may keep the CEL from coming ON, your cat is still GONE.. (clogged, etc) and the performance aspect of the car is still hindered, you just aren't getting a visual representation of that fact.
MILS are wonderful, but are most helpful when you remove the pre-cats (headers, etc) Simply tricking the CEL to stay off, while having clogged cats is ONLY keeping the CEL off.
(Not trying to preach, etc.. This wasn't really directed at you, just using your particular situation as a post for posterity to other users in the future)
Ray
