depends if you want traction or not.If you just want to spin or just catwalk the sled...the bigger gap on top is the way to go..of course you will have no steering and look cool with ski's in the air..girls like it also..lol
More gap on top,more the skid couples before taking the front end with it.
50/50 gap should give you all around good traction and not raise skis by much or at all.You will want to read betheviper's article on this and it tells you how to set up everything.
It may seem you have more power and am faster with ski's up in the air,but actually you are slower.You want energy to take you forward not up..