I had an 06 and the main problem that I had was the rear end bracket. Mine was under warranty so I did not change mine but there is a stronger rear end bracket out there that the dealership told me about. This stronger bracket is supposed to remove some of the wheel hop. I put 70K miles on mine and did end up with a new rear end but most of the troubles occur when you put too much weight over the rear axle and accelerate hard. I never had any issues when I was in my car by myself. Every rear end bracket was when there were people in the back seat. The 09 and up V's don't have any of these issues. They are all really fun cars. Stick with the Caddie, the GTO doesn't have a better rear end, just less frequent rear passengers.