It will cause premature belt wear.

 

kylightning- It does seem more logical that the flat face goes on facing the front, I almost put mine on that way! But that IS NOT the case. I checked around before pressing my hub on. Like evilguy said, it will cause premature belt wear because your belt is not gonna be aligned right. Im sure if you will look at the pulley you will notice the front part of your belt is rubbing on the front inner most part of the pulley. It will still work ok, you may be replacing belts though.
Did you notice a diiference in the way it runs yet? It helped mine quite a bit.

 

hey i got the pulley on. i just bought a bolt that fit in the blower snout put a nut on and 3 washers in front of it. then held the pulley in place with vice grips and screwed the nut inwards. it was a pain in the *** but it worked.
truck runs great

 

yes i noticed a difference. i boosts faster, i can only imagine what a lower pulley+fan+water pump and traction bars could do.
a day before that, i put on a flip chip, the two together plus a few other mods i have and the only problem i have are traction, big difference.

evil guy--how hard is it to pull off the hub and what do i need? help