anyone know of any good brands and if i would need a new belt to go along with it?? i also now that its only the crank and the alternator pulley and am curious at how much of a horsepower boost it would give??

 

they are supposed to give you like 10 and i dont think you need a new belt

 

You will not see 10HP gains on an LT1, because the water pump is not belt driven. Do a "search".... the link to a dyno test at ws6.com has been posted numerous times. It gained 0.7 peak HP (yes, 7/10's of one HP) and 4.4 average HP.