The stock tabs are weak. There's a considerable amount of force transmitted through them when you corner, and the harder you corner and the stiffer the swaybar the worse it is. Stiffer springs actually help by taking some of the load off the swaybar. If you have access to someone with a welder (most shops can help you out), just drop the subframe and have them weld it up a little. It's cheap and easy insurance. Should be about $50, maybe less.
