Keep trying to contact Tony and TVT...they are the one's who need to deal with this. This is your first post on this forum, so from that, I assume you haven't searched thru the threads dealing with the install of these parts. That would be the next step. I am not going to bash TVT or Anthony. Your friend is probably a great mechanic, but is he a certified MB or XF mechanic? You need to keep trying TVT to get to the bottom of your problems. Just my .02...