Martin Crisp authored the XXX-main setup guide (good guy, and an awsome racer, raced with him in 12th scale & touring a couple times, he's fast
) . The XXX-main guide covers all the setup stuff you need to know about touring cars as far as setup goes.
So, things I would like to see that are not covered in the XXX-main guide would be:
1. Quick chapter about the history of RC (from the old flexi RC500 days till now, etc..)
2. Overview of a typical modern day car. Telling what particular things do (why a one way? Why a spool? 3 belts why not two? Clutch gap?, etc..)
3. Engine overview and tuning (why 3,5,7 ports? what pipe? golw plugs? fuel?, etc...)
4. How to race an RC car (throttle control, apexing corners, worthwhile practicing, etc..)
Good luck.