Vanilla vampiric drain is 2pts per second in stage 1. in master difficulty it will cause 1 pt of damage per second... ONE POINT PER SECOND!!!... GET READY ALDUIN! I JUST BECAME A VAMPIRE AND I'M GOING TO KILL YOU...NEXT YEAR!!! 

This mod increases the vampiric drain in human form to make it useful.

stage 1 - 8pts per second
stage 2 - 10pts per second
stage 3 - 12pts per second
stage 4- 15pts per second

it also boost the magnitude of the dawnguard buff that absorbs stamina and magicka by the same amount.

It may look like a huge unbalanced change, but it's not. In reality vanilla drain is unballanced weak.

Take a look at my other balanced changes:
http://www.nexusmods.com/skyrim/mods/85011/?