griffster - Eibachs can be fine, as long as the damping is correct. This is why Eibachs on standard shocks is not a good idea - the damping is simply too weak to control the firmer spring
I would advise against mucking around with tyre profiles - you'll make your speedo inaccurate. Stock to 205/50 16, 225/45/16 or 215/40/17
I'd agree on that, and plus that fine 225/35-18 alternative.
Also agree on the Eibach's, not much wrong with them, but the problem with the std dampers is not so much weakness as wrong spectrum. Lower a std Coupe and the shocks are in full-load-mode, hence HARSH. The Bilstein B6 or Osrav's have a wider/lower 'normal load' range and so, comfier.
Also; when swapping shocks, do please mind the length of the front shock cylinders. In the case of the Bilsteins they are much longer than std, making the Coupe sit on it's rubber bump stops. THAT is crashy, but surprisingly common..
Very easy fix though; cut them rubbers a bit.
Also 2; on my car the battery-move-to-the-rear actually made a greater improvement than the famous strutbrace. (yes you probably have to try it to believe it)
And the lower strutbrace did even greater effect, though it is a good idea to mod it a bit. It's too often too close to road obstacles, I read.