User blog comment:Mineko Charat Lucky/Touhou LoL - Momiji, the White Patrol Tengu/@comment-177.40.109.124-20130112143431/@comment-5791947-20130116120727

Assuming Momiji wih +, she will have a raw movement speed of 504. Because the soft cap of Movement Speed is 415 and hard cap is 490, this is reduced to 482 movement speed, minus 245 base movement speed. This yields 237 extra speed to her resource pool. But because activating only increases the resource cap and not the resource itself (this is also why I don't recommend  or  in her build, since temporary movement speed buffs don't benefit speed champions much), she still has a mere 275 out of 437 speed when activating Youmuu's.

Now then, a typical Momiji combo would be ERWQ, casting E first to boost her movement speed to a raw 575 movement speed, hard cap to 518. After the cast, she will have 225/473 speed.

Next she will ulti, dealing 200 (+ 273) magic damage and a further 200 damage, yielding a grand total of 673 magic damage. This does seem ridiculous for an ultimate...

Using the ultimate drops her resource down to 125/473, next she'll cast Maple Shield, costing 80 speed but since the ability allows her to travel, she recovers at most 60 speed. Assuming Momiji can hit directly at the end of her distance, she'll deal 260 (+ 21) damage, with 105/473.

This gives Momiji barely enough to cast No-no Slash, remaining at 45/473, dealing 312 (+20) (+12) physical damage to a stunned target and 240 (+15) (+9) to anything else.

So the total damage would be 673 magic damage + (281 +  344) physical damage = 1298 damage.