[Bill Edgeworth]

It’s a very common mistake that many people only look at ballast and weight distribution based upon static conditions. You really need to look at what happens during the dynamic state of the car (acceleration) takes a little bit of math but if you do a few vector calculations you will find that weight added behind the rear axle, depending on position in relation to horizontal and vertical centerline of the axle can actually take weight off the rear tires during launch!
The simple analogy is to take a look at all the ballast behind your axle centerline during launch and realize the fact that the rear tires are pulling it along not pushing it. Then ask yourself if the ballast is helping pull the tires down or up. There is a book called “Door Slammers” written by Dave Morgan who Travis mentioned which goes into some fairly good detail on the subject.