How many miles do you have on the cats?
I've got over 165k miles in my '99 and it's 100% stock, CA emmissions setup. I only have a K&N intake kit (CARB legal) and this truck has passed every smog test with flying colors...
a complete MSD ignition setup does help it alot, but still, all the exhuast parts including the cats and O2 sensors were original.
I have another track car that is a **********in pain to get smogged, so I left the truck relatively stock (exhaust wise)... and thank god!
I do feel your pain in the search for cats. though... I tried to source out some better performance, CA legal cat setups, and they are hard to find, and almost double the cost!! so I just kept her stock...