Choosing the Correct length shocks:
Let me break down a few options for you.
Option 1:
Take some pictures of the current set up and maybe we can figure out what you have. If they are Shockwaves (bag around shock), then we can figure out a direct replacement as we know the dimension of the Shockwaves we've built.
Option 2:
Since you are using TCI clips you may want to call them and ask what their compressed, extended, and ride height dimensions are for the shocks you currently have.
You can then call us and we'll set you up with the correct units.
Or look them up here:
http://www.ridetech.com/store/coil-overs/
Option 3:
If you don't like talking to anyone you can do this simply by stroking the suspension, measuring compression, extension, and ride height, then choosing the closest match from this page:
http://www.ridetech.com/store/coil-overs/
Spring Rate:
I would not trust the spring rate anyone tells you! Not that these guys aren't trying to help, it's that no one out there has the exact same car that you have. It's better to throw a little math at the problem and get a correct answer for your specific vehicle.
The spring rate is easy to figure once you have some data. Just enter the info into our spring rate calculator and you'll be given 3 options. Remember, the spring rate calculator is only as effective as the information it is provided. If you gather all the info it will give you the rate you are looking for. If you start guessing at some info, you may not end up with a good rate.
You can do it yourself here:
http://www.ridetech.com/tech/spring-rate-calculator/
Or you can call us and we'll walk you through it all.
812.481.4787