So if you are looking to run a set of Koni inserts , Tokico D Specs or KYB AGX with 2004 + Wrx rear tophats you are going to run into a little issue where the struts make a horrible tapping noise when the rear struts hit a bump. The reason for this is that the rear tophats changed from 2002-2003 to 2004 + and you need a simple spacer to fix the issue.
The spacer can be found here
This is where its installed on the strut assembly
Konis with a 1 inch lowering spring look great too !