I personally have a 10kw Powertech powered by the Kubota small 4 cylinder. Very satisfied with it-has tight voltage control and haven't had any problem with it in the 12 years I've had it. I looked at Norpro-they strike me as a new company. If I were you, if I lived on the right coast, use Powertech. If you live on the left coast (or which ever is closer) I'd use Wrico, with using Wrico anyway as my choice, since Dick Wright is so active in the bus conversion society. Good Luck, TomC