Im running exotek rear hubs and I like the 10mm tini ball studs for 4 to 6mm and 12mm tini for 8mm. That way yo get plenty of thread engagement. Same for the inner studs. (Note:Exotek hubs require 2mm to be stock height so +4mm is actually +6mm on those hubs requiring longer studs to achieve the same result as the buggy hub mod)

I found that raising the outer stud to 4mm kept my truck from traction rolling as much meaning I get more camber as the truck leans because the tire stays flatter to the track surface. This works really well for me on indoor bluegroove. I use the m2c toe block at 3.5deg for more forward traction.