For future search reference...The Eibach springs provided by Ground Control are not pro kit springs. They are the ERS springs, which are a more universal line of springs in regards to diameter, length, and spring rate. They are also warrantied for life against sagging. All GC brings to the table is a fancy anodized red sleeve over.
A cheaper way to go about this setup is to get a sleeve over for short money then source some used ERS springs of your choice from a racing forum. They swap out springs all the time adjusting their setups. Generally they sell for $30/ea
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