The Eibach Pro-Kit springs are a good choice for you. If you do daily driving, and just want to lower the car and improve performance slightly, the Eibach will definitely work out for you.
Here is a link to the exact part...
http://www.stangsuspension.com/store...p?idproduct=82
With 45k miles, I would definitely suggest purchasing shocks & struts at the same time. Your OEM shocks are worn at 45k miles.
If you install new shocks & struts, it will help dampen the newer/higher spring rating of the Eibach's, and will control the ride much better. The Tokico HP's are a good match...
http://www.stangsuspension.com/store...?idproduct=938
Sincerely,