On a stock mustang, how much will lowering the car effect the handling? I don't go the track at all, but I love driving fast through the hilly streets of northern Georgia. So would lowering the mustang really help out that much? If so, is there anything else I need to do if I lower it? Looking at the Eibach Pro-Kit Springs
Really depends on the spring rate of the lowering springs compared to stock. If you wanna get new shocks and struts when adding lowering springs that are adjustable you can dial them in to be tougher to help with handling. Depending on what you go with and what the spring rate is, it will make the car handle better AKA taking a turn harder.