If you are talking moving weight..... The more weight of the car, highest percentage, you can put on the rear the better. Better weight transfer, in theory, the better the car will hook up. Of course there are so many varriables it's hard to say. Like don said torque, torque, and you got to get it to the ground. You could have a 7hp per lb advantage over another car and if you blow the tires off......well guess who will come out ahead. Of course that's a drastic exageration, but you get the point. With any race car the lighter the better. Then if you have a weight minium you put it where you want it. And with a very light car, and no weight minium, you may find that adding weight to the rear, will make car hook up better and better et's.