first off, you have to replace all 6 small wheels in the skid with 5.350" AND the rear wheels to 7.50" to get the full effect!! this keeps the entire skid on the same plane, when you let off the gas the sled will coast like a motorcycle not grind to a halt, you will definitely know it!! frictional loss eats up power, the easier you can make the drivetrain roll the faster the sled will be! the added benefit will be hyfax will last forever and the sled will make the track come up to speed faster.
theres lots of things you can do to make your sled roll easier and this means more speed and better gas mpg. For instance run a 21 or larger top sprocket,bending the chain tight around a 20 tooth or smaller sprocket is harder on the chain and creates more frictional loss then a larger sprocket does, its the same exact thing as the larger track wheels in the rear, bigger the bend easier to turn the track around it.
Make sure the chain tension is correct in the chaincase, you should have about 1 inch of side to side movement when you have the correct tension on the backside of the chain(non tensioner side), meaning you can move the chain to the left about a 1/2", then move it to the right about 1/2" this is 1 " movement together, this is often overlooked.