Stiffer in the front will leave the car with a little understeer. It will be safer if you don't know the capabilities of the suspension because the stiffer rates in the back will result in a little bit of oversteer, which can cause the car to spin out.

The good thing about Ground Controls is that the springs are interchangeable. Say you ordered 350 lb/in and 450 lb/in springs. You could either choose to put the 350's in the front, 450's in the rear or vice versa.