so, you want me to put a scale on my jack and jack the rear end up and see what it wieghts or what?
I'm not exactly sure what you're looking to find out...
Are you wanting to know what spring rate we all use on our coilovers?
Also, if you adjust the coilovers down so they are shorter, they adjust against themselves, so it doesn't matter what the car weights, it will still get lower.
Maybe I'm just not getting exactly what you're asking...