What I would do is invest in the Skunk2 full coilover setup instead of just the springs. They are more costly initially but after replacing the factory struts every 2-3 months at $65 each you will save money in the long run. They include everything you need to just pull the whole strut/spring assembly from the car and replace it with the Skunk2 full coilover. You dont have to change the springs or anything. Plus another advantage is that it will ride just like stock at no matter what height your car is lowered to. They are adjusted from the actual strut mount instead of the sleeve so the strut has the same travel whether its slammed to the ground or all the way up.