My advice on the nova revo cups.

[Serum]

My advice is to stay away from them as far as possible.

Three points of flaws in their design;

-they are too large in diameter and don't fit the stock housings.
-green line; too small, the rubber gasket doesn't fit, it doesn't want to stay in place
-red line; the flat spot is too small, it's tapered, so it's even smaller, rubber gasket will be pressed out on that point due to it

What you need to make them work; blue silicone loctite on both the cup and the screws to make them silicone-oil tight. and you also need aluminum diff-housings. I got 3-racing housings, which are large enough to mask their too large diameter error.

I am glad Mike is currently developing the 1/8th diffs.

I contacted nova about it, but they are too arrogant to talk with.