The stock rear springs are to soft for any kind of high performance driving. I added an extra leaf on each side and it stiffened things up. I used a main leaf from an old pickup with the ends cut off. I don't recall what kind of truck. It was thicker than the stock leafs but the same width. The car handled much better than a stock Mustang. I gave them to a friend when I had the car apart. Now I might have to make up another set. I'm going to try coil over rear shocks first and see if that helps. Is that what those Sensatrac shocks are? Let us know if they help.

I got an export brace to stiffen up the front. Sub frame connectors are another option to consider.