With EFI and mechanical fan the Powermaster 50A idle/75 amp max was not enough for me. Even going down the highway with AC and bright lights on it barely kept up.

I replaced it with a 100+ amp "big chrysler" alternator with great idle output and that works fine... just heavy. I had previously tried the 140 amp GM derived Powermaster alternator and it hit my aluminum heads.

With electric fans in addition, I think you need at least 140 amps... and plenty of idle output.

I guess you are running AC? If so, the "with AC" brackets make fitting a non stock alternator challenging. Next upgrade for me is a "Quality Power" unit which looks nice, just spendy. At least one board member is running one though I have not heard an update.

http://www.qualitypowerauto.com/item_557/Chrysler-Mount-Mega-Amp-Alternator.htm