Supposedly these were quite economical engines compared to the Frog 150 they derived from-and for a while were popular in the 80's for the UK's 'Flying 15' class-which was a UK type Texaco event. Being a sort of reed valve setup, they'll run either direction-I have two of them-which raises thoughts of a C/L twin one day and possibly opposite rotating props......
Performance wise they're better than the early silver head 150, (and better than a Sabre, Hornet etc) but not up to the later 150R bluehead

ChrisM
'ffkiwi'

PS I've never done a systematic test of their fuel consumption compared to the other Frog 1.5s.......another experiment to do one day.