IMHO, Upsidedown forks are one of the biggest blights foisted upon us dirtbike riders. A handful of Supercross riders deem them necessary, so we ALL have to put up with them. USD's are more prone to seal leakage (mud and dirt goes to the bottom of the leg where it is driven into the seal area upon full compression) too. Gimme a set of WP 50mm Extremes any day!