That could explain it, perhaps OS have out sourced the manufacture of the crank cases, and they are a fraction off what some of the previous motors have been machined to.
The difficulty for me here is, the N7 has come with slotted clutch stack mounting holes, but not the motor mounts. So, unless Synergy were to sell shims, where else would we buy them? Obviously I was lucky picking up old stock of N9 ones, but these are discontinued. I know of no other 'current' airframes on the market that use shims. I would have preferred to have seen adjustable motor mounts as well to cater for all motor variations like the ones manufactured by KDE for the T-Rex 700n. These have been perfect on my old 700LE.