i think id stick with the 33's. youre gonna have tons of top end as it is.. youre gonna need all the bottom end you can get.. ive always said, and others will agree, that cubs are NOT trail friendly. add shearers and you have an even less trail friendly bike.. i really think that you would be better suited doing a stock cylinder 4mm motor ported for your style of riding.. i think this cub motor is gonna wear you out in the trails. and i will also say that i think it doesnt make sense to de-tune a cub motor.
just tryin to give you some honest opinions from someone who had a 4mm cub and now has a 10mm cub.