[bruinsh]

i have the one piece UDP but have not installed it yet. from my understanding, the 1 piece is freeing power away from JUST the AC. The 2 and 3 piece ones are freeing power from the AC and i dont know what else. thing is if you use a lot of stuff in ur car but dont really use the AC then i would go with the single. if you just want proformance then i would go 2 or 3 piece

 

[old_grendel]

the 2 pcs fc udp's replace the crank, water pump, and i believe the 3 pcs has the alternator...they also let u keep the stock belt...usually a 1 pc just replaces the crank and u need a new belt as well

in answer to ur question udp's are all pretty much the same...supposedly afx has the smallest ones hence underdriving them EVEN more, but i personally couldnt tell u one way or another

 

[craze173]

You should also look into the unorthodox underdrive crank pulley. sportcompactcarweb.com used this brand in one of their project focus'. It is the brand I bought as well, after reading thier focus project articles. It looks high quality and the price wasn't to bad, a bit high for a round piece of metal but it could've been worse. You should check them out.