Recommendations on Bohlender Graebener 512's

I like the airy sound of my BG 512's but would like more top end. I have the BG 512's hooked up to an EAD TheaterMaster 8800 and PowerMaster 1000, ModWright Sony 999es, NHT subwoofer, Tice Power Block lll and Audience AU24 I/C and speaker cables. Any suggestions from other BG owners on improving the sound (crossovers etc).
The BG's have a great midrange but have a limit on upper and lower extension by the nature of those large ribbons. Wisdom uses proprietary ribbons and Genesis added tweeters.

Brian at VMPS might have something if you don't mind tacking another pair of tweeters on top and adding a 7kHz or so crossover. I'm thinking of their directional FST as used on the Elixer.