Wow! Those look great-
I've got the Kenny Brown Extreme Sub system which is similar but comes with the traditional subframe connecter as one piece, and the jacking rail/cross braces as another piece that gets welded to the subs.
Was there any problem getting them to align correctly and contact everywhere that they are supposed to be welded? Curious, because we fiddled around forever getting the Extreme subs just right.
Sweet looking setup!