Check one last thing before diving into the S/C check your idler pulley. It is to the bottom left of your S/C tension pulley. I had a very similar issue over the holidays. 150,000 miles on a 97 gtp. Bought a rebuilt S/C, ZZP aluminum lower intake manifold gasket and tore the entire thing apart and back together in a 1.5 days. (First time). I go to put the S/C belt back on and while threading the belt I notice that this pulley has way too much side play. After taking the thing off I see that it is missing half of the bearings. Back to Napa and $34 and 45 minutes later all is done. Like everyone else I assumed the noise was the rotors and had no clue it could just be a pulley. Not saying I am enjoying the new S/C and air intake that I added, but simply replacing the pulley and just spending 45 minutes would have saved a ton of $$ and time.
