I installed an Afx underdrive pulley on my 2005 neon about a month and a half ago and in the past 3 weeks or so my belts have started to screech especially the first start of the day. The pulley came with the "correct" belts so does anytone think that it might be my tensioner or mabey the belts included weren't correct.

 

Your belt tensioner is probably bad. This same thing happened to me and i eventually made the dealer replace the tensioner...problem solved.