If you re-arch the springs over the point where they're flat, they stop working!!
I've seen too many guys do this. Stick with the lowering blocks, and add some trampbars. If you re-arch the springs, keep it sensible!

The other thing with coupes, is that the rear shocks are at a 45 degree angle as stock. If you re-arch the springs, the angle gets more acute, and the shocks dont work!
Lowering blocks dont cause this problem, as the bottom shock mounts are on the lower plate, and the lower plate stays in the same place when you add lowering blocks.

Other than that, check for enough clearance between the bump stops and the chassis rails.