I am looking at installing new coil springs as my car is sagging. Sits around 7-1/2" at the front of the door panel and maybe an inch higher at the rear of the door panel. Is correct height around 10"?

The reason that I ask is I am looking into finally getting new coils (have original coils right now) and want to communicate with mechanic correct height. Unless just installing the coils will automatically correct the height.

One last thing, do I need to coil insulators for the rear? Thanks!