paul
from what I can see these holes can effect the amount of droop the back wheels have. i've tried them all and gone back to the middle hole, couldn't tell any difference, but what do I know!!!
I got some new ball cups which were the same as the kit ones cos they're dirt cheap, but I have seen people with white losi ones on.
All depends on personal preference at the end of the day. I don't think i'd go much faster with titanium balls.
Brett