The "wobble" is very slight. Caused by the little bit of play in the tilt adjust pin when it locks to the hole. Just mentioned so nobody expected "rock solid". I have the 20" and it will adjust over a range of 2 inches. There is also the tilt adjustment. I haven't fiddled with either one very much.
Interesting did you mod the tune. Top speed on the new rocket is 138 miles per hour under good conditions. Now they do make the speeder lie to you to make you feel good.