Originally Posted by Pro ten Holland

The steering turnbuckles level should be a good starting point. If you start changing that, you enter the difficult world of ackerman settings.
In a nutshell: ackerman defines if your car generates more toe-in or toe-out when turning the wheels. Max efficienvy should be that your car doesn't generate any toe-in or toe-out when turning.
This setting is mainlly controlled with the position of servo and by placing shimms under ballstuds etc. This is generally something I don't want to mess with too much. I let the boys who are designing these cars figure out the optimum setting!

Another thing that's influenced by placing shimms under the ballstuds is bump-steer. Again in a nutshell: it's how the steering angle of your car changes as the suspension is compressed.

As general advice: mount your servo the way it's described in the manual (same size servo saver, servo position etc.), than you're safe. There's already too much things to adjust on these cars. Just make sure the steering links can move freely without touching any of the suspension parts in any position.