i will chime in a little bit on damping. what Fred states is true but i believe there is more to it than that simply because of the technology in oils,chassis setups and tires. there are many ways to skin a cat and this is how i go about it. in general you want to run as light as oil as possible and not chassis slap to the point where it upsets the car, a little slap will not hurt you but if you land a jump and the car squirts around then go up a half a point until you reach a compromise (more on compromise later!) keep in mind that your oil and pistons size/number have a major effect on how the car handles as far as weight transfer, turning, accelerating etc etc. have you ever wondered why putting the same piston oil in front and back does not work? this is simply due to shock location and leverage, front shocks are always mounted further inward which increase leverage its as simple as that!
the thicker you run your shocks the more sluggish the car will be especially in our old dinosaur tech shocks, think about it if it takes longer for the car to transfer weight it will not be as agile especially through quick left/right turns and also jumping will suffer as you will get very little rebound to get the car in the air.
i have sitting in front of me literally about 25 sets of experimental pistons, over the past few weeks i have come up with some very good information and soon to be released piston kits. Fred has been fortunate enough to see first hand how my car handles and jumps, first weekend out i managed to break the track laptime record by .5 sec in 4w mod and .4 sec in SC with only these piston changes1 but before we get to that lets discuss the dino shocks! the current trend is big bore/multiple holes and for good reasons, IT WORKS! but you gotta ask yourself how is that a BB shock with 12 holes and 30 wt "feels" the same as 2 hole 30wt on a std size shock? doesnt make sense, you would think that with that many holes you would need 60 wt to get the same result. well to keep it simple it quite simply is surface area/oil volume/weight of vehicle always keep these three things in mind when you are shock tuning. if you put 2hole pistons on a heavy Ebuggy it will never work with anything thicker than water simply because of SA/OV/VW. So a good rule of thumb is that the heavier the vehicle the more holes/volume you will need to compensate.
As you can already tell its more complicated than it seems but having the right combo can make or break your laptimes and consistency.unfortunately we are all hindered by not having the ability to seperate compression and rebound(building your shock to have hydro rebound is not consistent and not enough for off road). to go along with the tuning guide that Fred has drawn up, it makes sense for us to come up with the same idea with shock oil/pistons. what good is to have your springs perfectly tuned and then scew it up by not having equal damping on both ends? im a beliver in that you should never have the same pistons F/R due to shock location/leverage. so here is what i have discovered with single piston setups:
(these are my own piston designs and are 3.1mm thick, with .093 std pistons try 1mm holes)
2wd FRONT:
5 hole 1.1mm/40wt
2wd REAR
6 hole 1.1mm /40wt

4WD buggy FRONT
6hole 1.1mm/40wt
4WD buggy REAR
8hole 1.1mm/30wt

try these setups and get back to us with your results if you can, remember to start small on the holes (1mm)