Yeah, stupid really, because PS (Pferdest�rke) simply translates as "horse power" anyway. But the PS or "metric horsepower" is slightly optimistic compared to "imperial horsepower" or BHP (by 1.4% as I mentioned above).

So Yamaha's figure of 48 PS, which they conveniently rounded up from 47.6 anyway, converts to 46.9 bhp and therefore comes within the A2 limit.

More info on Wikipedia if anyone's interested.
http://en.wikipedia.org/wiki/Horsepower