Well, if you take a low-and-grow approach, you can recone and see if you like. If you're hungry for more, you sell the recones and get the new 416s from GPA. I am part of the 416 hype, but damn, they sound good. I just don't have the 828 cabinet, so YMMV. But what I like so much about them is that full mid-bass, and if the 515's have even more of that goodness, then I'm on the lookout for some. I still run a sub with my 416s.