It seems the norm for boosted brushless setups are 30 degrees mechanical timing, and up to 30 of boost plus turbo.
See the Hobbywing Xtreme Stock manual (which states true degrees of timing), giving 21 degrees of boost, plus a further 8 of turbo, for a total of 29:
http://www.hobbywing.com/upload/manual/HW-09-XST.pdf
In a situation where there's no motor limit, the greater efficiency of a lower wind motor and no ESC trickery, plus the simplicity of setup, makes boosted motors seem unnecessary. If traction is low, dial in some negative expo or lower the punch setting on the ESC.
The one advantage of boost is adjusting for different tracks without changing motor - just leave your gearing alone (set for technical tracks), and dial in some boost to give the car the legs on the longer straights of a bigger track.