[Dryhus]

The kick boots increase damage on kicks, not frequency of kicks. I believe the kung fu shoes make your kicks equvilant to how hard you'd punch with a +10 damage weapon on. Wu long are +20 (+25 on HQ) to my understanding. And dune boots are +30, again to my understanding.

The way I've seen it explained, normal kick attacks do the same damage as a single bare-handed punch at that level, meaning hand-to-hand skill plays a very large part.

According to MysteryTour:
Kung Fu Shoes do the same damage as a single punch with a D+25 weapon.
Wulong Shoes do the same damage as a single punch with a D+27 weapon.
Wulong Shoes +1 do the same damage as a single punch with a D+30 weapon.
Dune Boots do the same damage as a single punch with a D+30 weapon.