I don't really like what Steeda came up with when they made an "adjustable" rear sway bar. There is no real adjustability in that piece at all. It's just a very small very weak sway bar that gets attached additionally to your existing sway bar. The adjustment is done through the end links that have springs in them, so essentially it works like a really progressive spring, in a sense that as the suspension compresses, and the springs in the end links compress as well, and eventually once the springs are fully compressed, the secondary sway bar begins to function fully. So, when you adjust those end links you are not really adjusting the stiffness of the bar. You are just adjusting a point under which it becomes fully effective.
This leaves you with quite unpredictable behavior. No one in road racing or anything loosely associated with performance driving likes progressive suspension, whether it's springs, or this idiotic "adjustable" sway bar. If you want the car to be confidence inspiring, you have to have predictability, which is what linear springs, and proper sway bars are used for. My personal opinion: Don't waste your time. If you want a truly adjustable rear sway bar, you will get the one like Maximum Motorsports. That bar has many positions on the actual sway bar that allows you to adjust the stiffness of the bar by reducing or increasing leverage of the end links. This means that the bar is as stiff at ride height as it would be compressed.