G'day twostroker,
I know there were various power outputs with these engines depending on model, but don't know if this was achieved by a high compression head like the PowerPlus full crank engines of the late 70s.
I don't think Victa would lie with a label like that so they must have marketed an extra powerful domestic model that way. First I've seen though.
Get it going and see if you notice!
Where did you find it? You got lucky there. That would have grown legs fast if you hadn't got to it when you did, especially with that engine cover.