I quite liked the Fender flats that it came with, although they were a little wooly, although not in a bad way. I fitted my preferred EB Cobalt flats (I know folk have had spot issues with these but, apart from a free set I had during their GG promo a while back, I've been lucky) and they sound and feel better than the Fenders to me. However, I read a lot about fitting roundwounds to Mustangs and went with the D’Addario XLs, which were OK and nicely middy, if a little rough, but eventually I went back to the Cobalts and, to my ears at least, are just as good in the mix and are far more comfy to my fingers. Owners talk about how good the neck and pickup are on the JMJ and they are exceptional, but I feel that the tone control doesn't get enough kudos. It's the only control I've had that matches the one on my old '63 P bass for having so much versatility and varied tonal points. This may have much to do with the interaction with the pickup, rather than just a stand alone component, but all I know is that it works really well; snappy Foxton type tone to dub reggae and all stops in between.