393mph at sea level the spit XII would be ideal in the LA MA's. They were used in S.England to run down low level hit and run FW. It's performance tapered off much above 12k. Wasnt the LFIXe just a Merlin 66 spit9 with uncliped wings? Sort of like taking our spit16's 266 motor and putting it in our spit9 along with an upgraded wing.