I have one on my car, and on the over-run it transmits a LOT more noise into the car, but other than that it is fine.

It seems to be a bit hit and miss as to which cars the top bolt touches on. It doesn't even seem to be ARB dependent. Some touch and some don't (even on my 22mm ARB, I didn't have any issues). However, there are three really easy things to do to clear if it is an issue.
1. Grind a small amount off the bolt.
2. Grind a small amount off the ARB.
3. Modifiy the diff mount like this:


I have three of the normal diff mounts in stock, and then the next batch will all be modified as per the above to ensure there are no clearance problems with any car .