Well he got the eibach springs right? and they have them specifically for the XIs and are rated for a drop of 1". My Springs are B&G S2 Sport springs. They don't make them for the XIs, only for the I and are rated for a drop of 1.6" in the front and 1.4" in the rear. Could that be the difference?..XI springs vs I springs?
Only reason why I got those was I didnt want the huge drop that the B&G race springs would give yet I didn't want to be stage coaching either after putting forth the effort of removing and replacing the suspension. And I believe there are XI guys out there running on I springs...