Twisted, I would probably try 1.3 x6 hole pistons before you dump the oil and try a lighter fluid. You could probably go all the way to 1.4 x6 just to see the differences (I think this might not be enough pack) but again it really depends on the size of the jumps and how many bumps and how fast you are trying to go through them. You may need to go to a slightly lighter spring as you go to less dampening as well.
side note here, the way you build your shocks also affects the amount of pack. Its possible to build more or less pack into the shock depending on how much you bleed when you build them….this is a bit more advanced but to keep it short: essentially how much rebound you have (OIL ONLY, NO SPRING) means more pack…..