IMHO the NVH kit is a boat anchor.
Would it be a brave person to mix some carborundum lapping paste with the EP140 and run it for a few miles at different speeds then flush completely an re-fill with new oil as an experiment?
Might not do the bearings nay good though.
I know people say the "wear in", but with lapping compound in the BB itself, you still have the bearings and seals that would have the same wear in as the gears.
My belief on the specialty guys doing the lapping, they have fixtures that hold the individual gears outside the BB and then reset the backlash and gear depth when re-assembling the BB. They would also probably vary the depth and the centering of the pattern so as to have a smooth gear face slightly larger than the final setup face to face area.
Even when they wear in naturally, my guess is that the backlash will become slightly more due to the slight wearing in of the gear surface.
I think it would be best left to a professional to do the lapping.
