how much power can a stock center diff handle

[2Point3TSi]

Power isn't really the factor here it's maintenance and how it was treated. Center diff's aren't really a problem unless you are constantly launching and don't have a good fluid in there. You number 1 easiest thing to do will be to drain the fluid and look for any signs of metal in there. Other than that another signs is making tight turns the front tires will pop as they are turning different speeds. Try making tight corners and listening for noise. Also raise the vehicle all the way off the ground and listen to the transfer case and diff's. It does however sound like a clutch issue though.