Audi told me that there is two different belts... one with 152 teeth and the other with 153 teeth.... does anyone know if there is a difference? Someone told me that they changed the tensioner and that's the only reason there is a different amount of teeth.

C

 

That is about all you need to know. The older 1.8t's had a poor tensioner design and it has been updated. When you update the tensioner you update the belt as well.
Call Avalon motorsports for a timing belt kit 303-400-3001 or e-mail at info@avalonmotorsports.com