http://www.wowwiki.com/Speed и подобное
The highest rank of Sprint, for example, temporarily increases a Rogue's movement speed by 70% (that is, the Rogue is moving 170% of the speed of an unmodified character). If this Rogue got the Minor Speed enchantment on his boots, which gives an 8% speed bonus (allowing the Rogue to run 108% of the speed of an unmodified character when not Sprinting), he could then Sprint at 183.6% of the speed of an unmodified character (because 1.70 * 1.08 = 1.836).
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The fastest sustainable land speed possible in the game pre-BC seems to consist of an epic mount (100% speed increase) in conjunction with the [Carrot on a Stick] (3% mounted speed increase), Riding Skill enchant (2% mounted speed increase), and [Mithril Spurs] (4% mounted speed increase), for a total of 218.5% of the speed of an unmodified character (since 2.00 * 1.03 * 1.02 * 1.04 = 2.185248). Shaman and Druid travel forms also exhibit this multiplicative stacking; the 15% increase they receive from the PvP-Rare set yielding a total SUSTAINED speed of 161%. The fastest sustainable speed on foot, not in a travel form, might consist of a Hunter with a Runeblade and the Minor Speed enchant under the influence of Aspect of the Cheetah, which would lead to a total of 151.6%.
не стакаются только эфекты, на которых что они не стакаются с себе подобными