Originally Posted by xxe92xx
so my question is would the stock belts fit on an aftermarket crank pulley?
Do you even understand what an underdrive pulley does? It is SMALLER in diameter so as to underdrive the accessories and not take as much power from the crankshaft. That means that you can't use an OEM length belt. The 2nd generation pulley setups in the DCT and 2009+ cars use a non standard double sided belt that is not readily available over the counter which is why all the companies besides AA decided to go another route in designing their pulley setups. AA decided to have some company make them a longer length double sided belt which apparantly has some reliability issues unfortunetly.