There's numerous ways. Bigger torsion bars, brakes, tires, sway bars, shocks, , rear springs, even full coil over and 3/4 link conversions. I do highly Suggest reading up on the Green Brick.
I'll repeat what Dukeboy_318 said........read up on the "Green Brick", 67/68 (don't rightly remember) Valient 170 2 door post car.....Richard Eherenburg, who was Tech editor of "Mopar Action" magazine owned and built it. It was surprisingly low tech, careful selection of factory parts, was clocked at 163 mph on the back straight of Watkins Glenn International raceway and only 1 car posted a faster lap time, this was against Vipers, Corvettes, BMW's, Porsche's, etc.
Cool thing is it still looked like Grandma's car...............
