Wrapping the cats with the heatshieds off would certainly reduce the heat transfer, however i would be a bit concerned that the cats would lose the air cooling and may run a bit hot.
You can all but try it as you can always remove the heat wrap if you do have any issues, just keep 999 on fast dial. :lol:
If you wish to stay with OEM cats with heatshields, I have a few decent preowned sets in stock.
Alex.