dont' waste you rtime with those plugs,.. there will be no change in performance. just get good plain plugs and you'll be fine.
as for the catalytic converter, i'm going to get it done soon as well as they will fail with the fuel available here. I should warn you that by simply removing it you could get a check engine light. I'm concerened about the sensors in the cat, worst case kkoool will help me send a signal back to the ECU with a modified emulator, i'll let you know what i found out regarding this process.