I have an Ibanez SR300 which has "DX" (Ibanez) P+J pups (P at mid and J at bridge) and a 2 band Ibanez preamp. This bass was like only $275 new. This is the old version which was discontinued in 2007. I bought it last month for $150 at a pawn shop with the intent of hot rodding it if I got some extra money. My questions: Is any reason why I could not upgrade just the J pup and leave in the stock J pup? If not, what would be the best brand? I've heard a lot of good things about the diMarzio P pups. Would just upgrding the P pup or even the J pup too, make enough of an improvement w/o also upgrading the stock Ibanez preamp?