I didn't have any. I did the 650 on my 2012 CTS V and picked it up a week ago. Couldn't be happier. I saw all the bad stuff being said about them so I went to the shop and talked to them before I decided to go ahead. I got the car back in 4 days as promised. All the pieces and parts were still there. I haven't taken it to the limit but I have pushed it enough to know to be careful. I got a nice wide open space in mind to see what it will do. I opted for the Corsa axle back touring. Now it sounds as good as it runs.