I'm lowered about 1.6" on Tein SS coilovers, with 205-45R16 tires. I have to be quite careful in spots.
I see no point in going lower than 1.75" for a street-driven car.
And I wouldn't bother with the Dropzone C/Overs. A bit of a no-name brand IMO. Sell 'em and move up to a matched spring and shock set. H&R's Cup Kit & Tein's Basic come to mind.

h:
My 2.3¥