they sure do...I tore mine apart like paper with a week's worth of civilized driving with the Aussie bar installed.
Bottom line is this - the Aussie bar will give you a tremendous improvement in handling and feel, the car corners much flatter and is a blast to drive afterward. BUT, modifications of some sort to the stock brackets ARE necessary (or complete replacement with custom heavy duty brackets...that's what I'm doing
) to ensure proper function and longevity.
IMHO the Aussie bar is totally worth it, just plan on doing a little extra to make it last.
