I'd heard and FMCP can review this, that it was when LP was going to quit making them and therefore supplying them to Modulus.
Honestly I can't see how mine could sound much better than it does. It's friggin' killer.
I have a 2004 Flea bass and it came with the basslines. It sounded sweet as hell. In November '05 I put a LP in it. Sounded sweet as hell still. It's not a huge difference in my opinion. The basslines is pretty killer.