So, I was over in NJ visiting a friend of mine and he happened to mention that his shop is now selling BBK kits on the cheap now. They make custom brackets to make the calipers of choice fit.
Their "entry level" kit consists of 4-piston calipers (if I remember correctly, it's Wilwood), pads, and lines, perhaps a few other things I'm missing. He says that you can have both the front and the back with the same calipers if you wanted to. Brake bias is perfect, according to him.
They currently don't have any brackets for E46 yet, but I will be driving down to their shop so they could take measurements. Then they will make custom brackets from those measurements and the kit will be available for E46 330's.
I just got the BMW Performance kit, but I never got the firm brake pedal I sought after with the kit. Performance is good, but I seek a firm pedal. I'm told this kit will deliver just that. And on the plus side, brake pads will be cheaper, around $100 or so versus the $200+ for 135i pads. If you have the calipers on the back as well, the pads are interchangeable front and back.
So, anyone interested in a BBK, you might want to hold on for a little bit...