When to Replace S/C Pulley?

Just picked up a 2003 double cab 4x4 with the TRD supercharger. The S/C is due for a rebuild so that kit is on the way. One video I watched suggested that the pulley should be replaced if the coating is worn off...is that a good way to determine if it should be replaced? I've heard that they're prone to slipping, does the coating have anything to do with that?
If I do replace it, I'm considering an underdrive (2.65") pulley. Reliability is a higher priority for me than power. That said, I'm in Colorado so low air density might mean I need the stock size pulley to make any boost. Right now the gauge never gets above 5psi, but I'm hoping the rebuild will help that a bit. Any thoughts on underdrive pulleys or whether the rebuild will get me back up around 6-7 psi?

 

If you have the stock steel 2.37" pulley, having the coating worn off is perfectly normal and not a reason to replace it. Also, nose cone rebuilds will not bring the boost pressure back up. The reason you are seeing below 5 psi is because of the altitude. At altitude, an underdrive pulley will reduce the boost pressure even more.

 

Got it, thanks for the info.
I was thinking maybe the rebuild might help boost because my previous supercharged truck seemed to pull a lot harder on the top end. It didn't have a boost gauge, so I can't quantify a difference in boost. This truck feels like it has similar boost down low, but falls flat on the top end. May be the difference between the manual and the automatic trans too. Should be interesting to see what it's like after the rebuild in a couple weeks.

 

Brand new gen 2 SC made 5 psi@1000ft in my case. Water methanol added 1 more psi.

 

The stock steel pulley does NOT wear out

The aftermarket URD pulleys are made of aluminum and a poor coating material and they wear out fairly quickly the smaller the faster. FYI.
a rebuilt supercharger will get u more boost depending