no mistake, i think the thicker the better in the center. i stripped one of the big gears inside the cneter diff, switched it but only brought 7k to the track and the truck handled like jello, the front end was ballooning big time and it was slugish to take off, also the back end was looseer. i'd do the 30k with a drop of 10k to slim it a tad, or 30k may be perefect. next i'll try 20+k in the center 10-15k up front and 3k rear, our track is tight and technical with tight jumps.