is the under/over 13 playable by just doing a hilo count plus adjustment iwth side ace count ??
i assume i need exceptuionally high numbers for this ??
Not as a practical matter. Hi-lo is too weakly correlated with the effects of removal for the over/under to be much use. It is better to abandon your regular count and use a specialized system for the o/u wagers. The gain from the o/u wager exceeds that from the main game if the penetration is reasonable.
Brett Harris markets an excellent unbalanced system called Ubalo that is worth purchasing if you can actually find this rare game.
Stumbled across this report by Snyder that might help you out. Do not have it myself, so I cannot say if it is any good (maybe somebody else out there has it?), but it is the only report Ive ever seen geared specifically for the over/under game. Also, it does say that there is limited availability, but here is the link anyway...toward the bottom of the page..