I recently bought a 2013 GT500 from a dealer here in Michigan. Come to find out their have been some mods done to the car, including a rear suspension upgrade with adjustable settings. It is black, but I could not tell what manufacturer.The car was making a slight popping noise when shifting at low rpm or getting on it at low rpm. The dealer replace the drive shaft and then the differential, but the noise still is there. They have now determined that it is coming from one of the adjustable arms on the rear suspension. Obviously not covered under warranty and they won't touch it now. There is no driving issue, just the noise. The tech showed me on the lift how one side is rock solid and the other has slight play when you grab a hold of it and torque on it. Seem to be right at the joint. There is a lot of knowledgeable people on here, but I need a shop to address this and my future plans for the car. I have no room at my house to do any thing other than basic under the hood stuff. Suggestions are appreciated. Thanks