[5point7]

I'd consider the .5 drop up to 3/4 inch, and would not even consider much more for the C. It's my daily driver. They will improve handling with the higher spring rates even with a conservative drop.
I have 1.5 drop on my 94 Mustang GT (not a daily driver) and I hit EVERYTHING, speed bumps, any driveway with any kind of incline etc. It's a PITA because I end up driving to avoid the road (I've even bottomed it on the freeway doing 60mph just by the normal freeway dips with 4 people in the car!! Scared the LIGHTS out of me it was so loud)...and if there is new pavement going in and the sewers are sticking up, better find a detour. Anything more than 1 inch is just too much IMO on the daily drivers.