I have a fiberglass 27T that looks a lot like yours. I am running coilovers on the rear. My current rear springs are 150#. The car rides just a very little stiff. I would think our rear weights are about the same. I think that 125 to 140# springs should be perfect. My car looks like this.
Just guessing, but looking at the length of your shock versus the length of your spring, the shock is bottomed out at ride height.
Does the shock go through the middle of the spring?
All the above questions are good questions. With some answers, we could get you straightened out.
Last edited by jaw22w; 03-09-2013 at 07:35 PM.