Bridge,
I have the BAT springs/Koni struts combo. I replaced the Eibach springs I originally installed because they actually increased the understeer. I'm much happier with the BAT springs because they don't lower the car as much, but the handling is much improved over the standard SVT suspension (itself already quite impressive).
The front Koni's are adjusted to full soft, while I adjusted the rear Koni's to a full turn stiff to balance out the handling. As BAT describes on their website, the ride quality of their springs is slightly firmer than stock. Since I replaced the Eibachs with the stock springs prior to the BAT springs I could immediately tell the difference; firmer, but definitely not harsh.
