Check Your Diffs - XB4 2015 spec
 

If you are running the standard steel bevel gears that come with the kit it may be worth checking your diffs. There is a hard plastic bushing (364990) that goes into the steel bevel (364955) which in turn the outdrive goes into. What I have found is the outdrive was binding badly in both diffs on the bushing and I am sure it was not like this when I built it, although I do recall it being a little tight.

I have reamed them out a little and it feels 200 percent better. Someone commented at the weekend that my car looked like it was understeering, I suspect I was running with the effect of very thick oils!

Anyway hope this of use to someone