Mike, I would guess that both of your Scalextrics are sidewinders and therefore could use about 1/4oz of weight just behind the guide. The Nincos seem to be pretty well balanced out of the box, although the NC-1 cars may still need a little nose weight. I find that 55-70% of the weight on the rear axle is a pretty good set up for non mag running. I like using the stick on tire weights and many tire shops will give you a strip or 2 for free. Have fun!