Where the best place to get some idler pullies and a better bov
for my p1sc setup on my 99 5.3.

 

I know some people have gone with the ATI Race Ready or Vortech Mondo with good results. I don't think you can use a turbo style BOV because they are made to stay shut except when there is a boost spike like when you let off the gas abruptly. As far as pulley's, there was some guy making steel idlers on LS1tech. From what I read there, they worked well but some people had problems with shredding belts because of the added weight of steel over alum.