There's a current ebay listing for a 4.8 litre conversion. 4 to 4.8 would be significant but I'm not sure how beneficial the increase would be from a 4.6? No I don't want it.........really

4 8 Litre Conversion KIT FOR Range Rover AND Discovery 4 0 AND 4 6 Short V8S in Lauderdale, TAS | eBay

Gary