Here's some crazyness about your classing.
5 speed? You should be in ST.
Automatic? STX is correct due to having something other than a) all open diffs and/or b)viscious limited slip.
What's your spring rate? People have had sucess from anywhere between 250lb springs to 500lb+ springs. Dependent on if your dampers can handle them.
What about alignment? I don't see any camberplates for the front, unless they're included with the Megans. I would get as much  negative [/edit] camber as you can in the front. And then toe out the rear a hair and go from there.