I know you asked for finishing advice, but I can't resist!
(I had quite a few winners in my day P)

Most rules allow graphite lubricant (usually used for locks, etc)
on the axles - use it!

I always made the car a bit under weight, then brought along some
plumber's putty to get it RIGHT up to weight by the judge's scale.

Happy racing!

--
Keith Barrette
AIM: Keith020
http://keithbarrette.net/