P0430 is the code for Bank 2, which is the front bank. There are actually 3 cats on a 2001: 2 pre-cats and 1 main cat, and that code is for the front pre-cat.
You have a few options here:
1. Try to get Nissan to replace it under the 8/80 long term emissions defect warranty or any other extended warranty you have.
2. Try replacing the Bank 2 downstream O2 sensor (sensor 2), clear the codes, and see the code comes back.
3. Get an O2 simulator from www.o2sim.com
to trick the ECU into thinking the pre-cat is working fine.
4. Find a pre-cat from a junked 01 or someone who is getting rid of a used one for any reason. I have seen many used front pre-cats for sale over at maxima.org when people get aftermarket headers.
5. Paying an astronomical amount to have Nissan replace the front pre-cat and O2 sensors.