10.5 boosted try the setups we have on the website:
http://www.teamtekin.com/hotwire/ESCsetups/index.html
Gearing for the Dex 10.5 boosted would be 81/24-25 on most indoor tracks. Layout and size are all factors of gearing.
I agree with Cpt. though. I run an 8.5 and often am in blinky mode which is no timing. Geared 87/26 last night at the local indoor track.