Anyone have any Pinewood Derby tips/tricks?

In the spirit of competition, don't look to the grey area's of the rules, this ain't oval track racin, it's about teachin the kid's right from wrong as well as teachin them how to build stuff. If I had official rules to post I would do so and will try to get a copy of them to post. We had a limited amount of space and without knocking down a wall we couldn't run all four sections of track and other than renting a place we ran the race with three sections of track. all participants recieved a trophy and a hot wheel's car and all of the little kids that attended recieved a hot wheel's car also.There were a few cars that did not pass tech and we either helped them fix the car or allowed them to fix the car before the races were started...but did so in the spirit of not leaving anyone out.....Hope I worded that right and hope the way we handled it was acceptable.as was shown in the pic's a triple beam balance was used to check for legal weight and a bsa tech go-no-go gauge was used to check lenghth, width, etc.