"I bought this set mostly because I liked the look of the alternate model - but it turns out tweaking the main one for ideal performance has been so much fun it could be quite a while before I get to that!
First thing I noticed before I'd even given it a test run was the multiple heights possible for the wheelie bar; the instructions didn't quite get this across to me but fiddling around I found 2+ lower positions including one that *looked* too low by eye but turned out to be just about perfectly in line with the front & rear wheels.
Then I had some trouble with the rear tires slipping on takeoff (even after cleaning the floor and tires - a little moisture improves the rubber/road connection); it seemed some slightly 'slicker' tires might be more ideal, but then I noticed the 42118 Grave Digger with its bigger tires was outperforming it.
Looking around at other models in the house I found a pair of 49.5 x 20 tires (compared to the included 42.5 x 22) and was impressed with how much better it worked despite the narrower tires. The tread seems to grip better and the bigger diameter boosted takeoff speed, without noticeable 'wheelie control' problems.
I'd like to try a little gearing along with some slightly *lower* 'slick' tires too before I move on the dragster build. Definately a lot of 'playing around' bang for your buck here! I'm looking forward to trying the 42104 Race Truck model as well,"