Almost every aftermarket kit comes out of MBM Brake Systems in NC. Retailers get their logo on the box and they're drop shipped.
mbmbrakes.com
Options are limited if staying with SBP, plus I stayed with the 9"
Went with different wheels (that I don't much care for). It resolved the issue. Had I known I probably would have gone for a 4 piston caliper solution if I could have found one, or bit the bullet and gone BBP where there are a ton of options for wheels