weld or bolt SFC
What I'm referring to is right down to the chassis itself. Your SOTP or hands CANNOT detect those things, unless the car is absolutely pushed to it's limit on either an autocross course, road course, or at a drag strip. Unless you have a racing seat with a harness, only your eyes will be able to witness this phenomenon if you are using your body's senses. What is felt is down to poor shock valving, not the chassis itself.
I highly suggest to get the car on a frame alignment machine (not suspension alignment lift) at an auto body shop, and have the dimensions checked before installing SFC's, that way accurate measurements are recorded and they can tell you whether any problems they detect are worth repairing or not. If it has a clean bill of health, then you can opt to put them on. If anybody else puts them on, they need to "dry fit" at least twice before welding to ensure that it is a working fit, otherwise many troubles will arise several thousand miles later.

