I have a Superlift 6in lift on my Dmax. CCLB with H2 315's. Other than replacing my cheap BDS shocks with Bilstein shocks, is there anything else I can do to improve my ride? I have 150k miles and the ride has never been great but is getting worse and worse. What do I need to do?

I have 1600 miles on my Pro Comp lift and I love it. I would assume it is your shocks, unless the T-bars are cranked?
Try better shocks, I have the adjustable Pro Comp MX 6's and I like them.