Motoblue Underdrive pulleys

[68mustang5.0]

Are these pulleys good? Will i notice a difference? Ive read of charging problems with using the alt pulley, but can i still run the waterpump and crank pulley? They look pretty cheap, i might order them. Thanks!

 

[Dalamar]

I did UD pulleys way back, I took them back off.
I think they're a waste of money, personally. maybe 3 HP, and you can get issues from the alternator not spinning fast enough at idle, could get hotter too.