Out of the box the car is great , we use Daz's setup on 3hobby.net.
Only real hassle has been the brakes and to change the brake pulley to a ally one.
Other than that std car is
Have had no issues with 5th body post.
Cant say much about the overdrive ,but a fellow racer just finished 3rd in Amains using stock car with only brake pad and brake pulley upgrade.