Alright, here's the deal:
i'd either gut both precats or none. It isn't really that hard.
First off, there seems to be some confusion with which are the precats. The precats are attached to the front and rear bank of the engine. The piece that connects those two is the y-pipe, not a precat.
In a nutshell, this is how you do it. Disconnect the battery and jack up the car. Remove the y-pipe, which would be 2 nuts on the front precat, 2 on the rear precat (the whole bolt may come off, which isn't a big deal), 2 at the catalytic converter and one nut that simply holds the whole y-pipe up. Remove the O2 sensor at the bottom of the front precat.
Use a screwdriver to gut the rear precat. Drill a 1/4" hole in the bottom of the front precat at the bottom of the bend, in line with the straight section of the precat. Use a bucket handle attached to a drill to gut the front precat. Start the car and blow all the crap out of the precats. Put the y-pipe back on and reconnect the O2 sensor. Hook up the MIL eliminators.
Done. There are how-tos on how to do it elsewhere that are more thorough than this description.