In reply to the SINGLE BEST handling mod for an e-body, away from the stock suspension, beyond ANY doubt it would be to increase the stiffness of the torsion bars. The factory bars of .89 hvy dty, or the .92 (hemi -six-pack, t/a, aar) all were far too soft!!! I've tried many different tb's, and have realized increased handling response with every increase, but I eventually ended up with the largest tb's at 1.24" (I purchased them from the now-gone "California Suspension - Calif Moparts") back around 1987). HOWEVER, you have to keep the overall setup as a "package"... stiffer leafs (FlexaForm fiberglass at 225lbs/5"arch), Koni shocks (would go with QA1 dbl adjustables, or similar, today), 1.25' front sway bar, 1" rear sway bar... and... equally important.. is to lighten the car where ever possible!!! My t/a is 3150lbs in race trim (SCCA Solo II class E/SP) with 1/4 tank gas (w/o driver).