I have an MIA Fender Jazz which has their "American Jazz Bass Single-Coil Pickups". Now, I'm sure that replacing the pickups on a MIM Jazz with Dimarzio UJ's or Bartolini or Fralin's would improve the sound because the MIM pups are straight up crap. What kind of sound/tone improvement can I expect by replacing the "American Jazz Bass Single-Coil Pickups" in my MIA with some of the above mentioned after-market replacements? The bass is alder with a maple/rosewood neck. The bridge is string-through. I have a J-Retro installed. Thanks!