[lxfiveoh]

Have you already stiffened up your chassis?
Convertibles could use all the stiffening they can get!

I suggest:

1) Weld-in subframe connectors
2) Maximum Motorsports strut tower brace
3) Lower chassis brace ("G-load brace" or Kmember brace)

Springs/shocks/struts

You can't go wrong with Maximum Motorsports stuff.
Try their caster/camber plates, some H&R springs, and Koni or Bilstein struts/shocks.

In connection with the chassis stiffening, you should notice a huge difference!

Good luck!