Although on earlier carb engines, LP gas could reduce emMisions 80 %, the move to soild state EFI has lowered the advantages somewhat. The catalyist is only partly effective on a LP gas vehilce because its light-off temperature is much lower...it never gets to 1100-1500 deg F like the gasoline (petrol) engines do. It's there as a legal requirement, and flows pretty well. Leave it there. Optimise the system as per XR6 practice. Just be glad you have an AUiii, and not the heavier and slower BA E-gas
The E-gas (148 KW?) Falcon is such a let-down compared to the earlier ones that just lost a fraction (5%) of the peak power. To loose 23% of peak power on a freeking rapid Barra 182 is nasty.