well...theoritically....you can drop a car by 4" at most but then you run the risk of bottoming out when you drive.
that slammed look you are talking about is usually meant for shows and looks only. its not at all practical to drive on that low a height...
plus...if u go that low...your shocks (even the best aftermarket ones like Koni, Tokico, H&R) will blow eventually...the only exception being full damping coilovers.
been there done that.....seen many loosers here bottoming out and loosing their oil pans and exhaust piping...haha
this is true for all compact and sub compact category cars....