Ace and Six
The H17 rule primarily effects the play Ace and the Six up-cards, in that order. It odes effect the rules on other up-cards (2,3,4,5, in that order; w with the highest effect, 5 with lowest), but those effects are much smaller, and usually not enough to change index numbers.
Doubling indices against an Ace become lower. For High-Low, double 11vAce at +0 and 10vAce at 3. Same for double v6, on things like Hard 8 and Soft 19. Those plays are not a formal part for the I18 and some players do not use them; but if do them they are about 1 point lower.
Standing numbers are also reduced: 12 v 6 drops down from -1 to about -3. If you playing shoes, you might just remove this index and make your strategy �Always Stand�.
Finally, and most important, there now become times when you would stand against an Ace. With a hard 16, you can stand at +3. With 15, stand at +5. These indices are NOT part of the I18, and I would recommend that you add them to your inventory if you play H17 games.
In fact, if I were to recommend an I-18 plays for H17 game, I would drop the 12v6, and add 16vAce.