I installed an unorthodox racing underdrive crank pulley a while ago back in summer and I have no compliants it has done me wonders in accleration and helps me pull nicely in high rpm's but now receantly I have been starting up my car and I hear a shreaking ear splitting sound coming from my engine bay, when I popped the hood It was coming from where the pulley is installed; I also got new belts with the pulley what can this be ?? how can I fix it ?? the weird thing is that it stays like this for like 20 min then stops and when I drive it does'nt make the sound, only when I turn on the car every morning.

Thank you, any info or input would help me a lot.

check the belt tightness and all the clearances of the pully and belt around any nearby obsticals

sounds like a loose belt. It screatches upon start up because the belt(s) get suddenly loaded and slips on the pulley. It is important however, not to overtightened the belt or you can damage alternator or water pump bearing, power steering or A/C compressor bearing. I have heard of cases too where tightening the belt did not help becuase the pulley got glazed. In such cases, you need to roughen up the pulley with 600 grit sandpaper or equivalent.