You get what you pay for...
It's really that simple!
The Baer kit is a whole new program compared to stock 4 wheel disc setups.
You need to modify the distribution block to allow more pressure to get to the rear for proper performance. Drum brakes work with less pressure, and simply bolting up a set of rear discs will not get the job done.
I can scan and post the mod according to Baer if anyone is interested...