You dont have to grind out the strut top bolt holes. You can use a Gen1 Series 1 Liberty rear strut top hat. It will allow you to use the GDB tapered rear springs while maintaining the gc8 rear strut top stud pattern PCD.

Having said that, unless you are going to get new G1S1 Lib rear mounts from subaru, second hand ones will have some pretty flogged out rubber on them so you may be better off just grinding the one stud hole so you can use GDB rear strut tops. GDB strut tops are a better design too.

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RS Liberty - Because WRX's are only good for parts...