I emailed Whiteline regarding to their sway bar rates and this their response:
Thank you for contacting us with your product question. The engineering team based out of Australia is the team that stores the sway bar spring rates and in the past it has not always been easy to attain them, proprietary info and all. What we do offer to the general public is a generic sway bar conversion chart which helps estimate the percentage increase in stiffness of the bar. Here is a link the above mentioned chart: http://whiteline.com.au/docs/bulletins/BL-281.pdf
Using the chart I can come up with the following estimations:
20mm Adjustable Front BSF45Z-
Soft: 38% stiffer
Hard: 70% stiffer
22mm Adjustable Front BSF45XZ-
Soft: 105% stiffer
Hard: 148% stiffer
16mm Adjustable Rear BSR53Z-
Soft: 38% stiffer
Medium: 71% stiffer
Hard: 117% stiffer