Spring rate
 

http://www.summitracing.com/parts/FMS-M-5300-B/

The front spring rate in these say 245/530... that seems like a huge progression to me. Is there any advantage to having ones that progressive? Before you say use other spring kits I NEED to have springs that still give a comfortable ride thanks to the terrible condition of the roads in my area. That and i'm in college and am only thinking of lowering it because there is 160k on the car and I need to go through th front end sometime soon.

I don't think that spring rate is correct. There is no conventional spring for a mustang that is going to have a 245 lb spring rate, even if it is progressive. 400 lbs is about the lowest you will ever see a conventional spring and for loweing springs 600-700 lbs is more likely. If you had the available funds, look into coilovers and finding a progressive spring with a rate starting around 200-250 lbs. Nothing is going to ride as smooth as a coilover setup with a lower rate spring.

http://www.3.8mustang.com/wiki/Popul...t_Spring_Rates

Not too sure about the spring rates but I have steeda sport springs with tokico hp shocks and struts. I couldn't hardly feel a difference from stock and that's on 18inch wheels.

How much did the whole setup cost you? And how much did it lower you?

I picked up the springs brand new from some guy that decided not to use them for $175 and the shocks and struts were purchased new for right around $300. The front was about 1 inch and the rear was a little more than 3/4 of an inch lower...measured with a tape measure from the floor to the center of the wheel well immediately after lowering the car down with ALL stock isolators installed.

Excellent, thats the kind of price i'm looking for!

The a very important part for you is going to be the shocks and struts if you want a nice ride. Do not skimp on those pieces as they will have a huge effect on the overall ride. For autocross guys, often the first thing they will do is change the dampers, and spends a ton of money on them too.