How much twist to use is a big topic of discussion...my general advice is if your boat feels "bound-up" (wanting to be pushed sideways rather than accelerate), induce some more twist. It's not really a science, it's more what feels right.
As far as doing that, the general consensus for cats is to crank on more downhaul on the main and lower your sheeting angle on the jib...that's all.
When you say lower your sheeting angle- do you mean more pull on the clew back or down? I am thinking that the more you pull the jib clew back you will allow it to twist off more at the top. just checking
