Talked to PSI today about how to set up these springs on a 2009 eagle head. Stock retainers are ok but the .640 Manley retainers are better. There is also a Manley titanium option but for the street I choose the steel retainer. Also on my head the factory 2 mm shim without the spring cage is ok. No need for locators. Installed height comes in at 1.94 .