When you have to stop after a hard left corner, open the trunk and pop the left rear quarter back out - my suspension was set up a little too stiff! I was autocrossing the car ('69 conv.) and it would "tincan" in right over the left rear wheel well when I got on the throttle in a left turn. And that was before we had sticky tires!

Bolt-ons are about half as effective as welded in ones, but you have to make that decision!