Atomic ball diff for Mini Z f1

[edhchoe]

Well, I swapped out the gear diff for the atomic ball diff. The car is making horrifying noise with the 6t pinion. I checked how the gears were meshing and they don't seem right at all. I put on the 7t pinion and they mesh better but the distance between them is too snug. I tried on the #2 motor guards and the gears sit too far and it is worse than when I had 6t pinion on with #1 motor guard.
What is everybody doing? It can't be just my car that's having this kind of problem with the aftermarket Ball diff.
Do I need Atomic pinion as well??