1997 Buick Park Avenue After market shocks.

I have poted prior about my rear end of my Park Avenue as becomming very stiff and uncomfortable. Through trying all different types of air shocks, replacing the compressor and sensors, I have searched online for aftermarket conventional shocks. I came across www. Strutmasters. Com and ordered them for my car. I am just wondering if the authors of this site have heard of or have any experience working with these shocks. The ride is no good still. I am just wondering if replacing the springs would help? The ride dosent bob and bounce at all, just very stiff, and read and talked to guys at Midas about how the spring is meant to give some give to the bumps in the road.