I recently picked up a used Pedulla Thunderbolt 6, and I restrung it with some Marcus Miller Fat Beams. I knew that the round core would make them looser feeling, and I thought I could handle it (heck, I have TI flats on my 4-string P bass!). Despite that, I've grown to dislike how loose the DRs feel, especially when I try to dig in. My P bass with flats is perfect for old-school jazz, but I want something a little more modern for when I'm playing more aggressive styles like rock. I'm looking to get a good, solid, J bass bridge pickup sort of sound (potentially something like this song, Goodnight Fair Lady by Coheed & Cambria). I would think that steel strings are the way to go for a really punchy sound like that, but other than the Fat Beams, I don't know what else to try out. Maybe Rotosound?