if its a 4.6 car? then convert to an 8 rib setup (search for GI joe 8 rib on Google) and use a Riechard racing 8 rib blower pulley....
if its a 94-95....convert your accessories to a 86-93 5.0 style setup....this will also mean to change the blower brackets, etc...then convert to a 12 rib setup for the blower....
Does it slip alot? A slight bit of slip just at acceleration will keep you from breaking belts. You wont get boost till you get up in the rpms anyhow. Kevin over at wicked put (i think) a 10rib on a d1 and couldnt keep a belt on it. He was pushing over 20lbs. They ended up puting the old 6 rib back on.