The Carvin pickups will have Alnico magnets. These provide a warmer tone than the ceramic magnets in the DiMarzios. I was just comparing pickups the other day, so the numbers are kind of fresh in my mind
. The Carvin C22s have a comparable output impedance to the DiMarzios, and are thus probably about as hot. If that's what your "stock" Carvins are, the main audio difference you might notice with the DiMarzios is that the DiMarzios will have a more "biting" tone.