Well ive ordered a 300 kit but i must admit ive seen stock RS250 hondas make over 78bhprw so im sure with some work a 300 can be made every bit as good as that.

A stock engined MC21 with the normal bolt ons should be able to make 65bhp and 31ft-lbs.

Dare i say it ive got graphs of Yamaha TZ's making over 80bhp.
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If I have to take the carbs off once more...