Just so you know, an engine doing 8,500 rpm is not considered high reving in the motorcycle world.
Of course motorcycles, when being used in high performance mode, have constantly varying revs and do not sit at any revs continuously.
It appears to have a watercooled cylinder and head which keeps noise quite low.
I did see that the 4 cylinder engine was listed without a gearbox so I do not see how this would work in a plane.