What springs fit my car?
A list of what parts fit what cars is here:
The cliff notes version is: 02-03 is mostly the same, and 04-07 is mostly the same, and you can make springs for one fit on the other as long as you use the right tophats. But that is ONLY the cliff's note version. Read the whole thread! Make sure you research whatever you buy!
What lowering springs exist? I want a really big list!
Here's a Google spreadsheet that contains most of the ones we know about
North Ursalia also has a good reference that contains a lot of the factory cars:
What's lb/in? What's kg/mm? What's the difference?
Lb/in and kg/mm are different ways of measuring how stiff a spring is. lb/in is how many pounds are necessary to make the spring compress one inch. A 100 lb/in spring with 200 pounds of weight on it will compress 2 inches (assuming there are two inches of travel). kg/mm is the same thing, but metric, like they use in Canuckistan. More info here:
Rule of thumb'ish: Divide lb/in by 55 to get kg/mm. Multiply kg/mm by 55 to get lb/in.
I have an STi. What do I need to know about lowering springs?
You're probably already on your bumpstops
What does that mean? Your car is MUCH more sensitive to bad lowering springs. Lowering without going stiffer means that you are going to be even deeper into the bumpstops - not good for handling OR ride quality.
IWSTI has done a lot more work on the specific STi woes than we have here so you should definitely spend some time there reading threads.
I have a wagon. What do I need to know?
Here is the master "wagon setup" thread (not just lowering springs):
1) Camber differences and how springs change them: Wagon struts on a sedan will make it easier to get negative camber. Sedan struts on a wagon will lose you negative camber.
2) Saggy butt: myth or fact?
I hear a lot about "pink springs" or "the pinks". What are those?
The "JDM pinks" are 252/217 rate springs originally designed as lowering springs for the Spec-C. There are a bunch of pink springs, but those are the most famous ones. The SPT pink springs are sold by your dealership
I'm thinking about buying SPT Pink springs for my WRX. Are there any cheaper alternatives?
You can get USDM STi takeoff springs at a small fraction of the price. The fitment rules above still apply, though.