well since F=ma, we can derive that a=f/m. The force is constant, you have a desired acceleration, and the mass is what will be varied. This will be pretty basic but should be somewhat accurate. Using R&Ts numbers 0-60 in 4.9, you get an acceleration of 12.24 mph/s(5.48m/s/s). You want about 3.9 or 15.38 mph/s(6.89m/s/s). We can also calculate force. The test weight of the car was 3430 in R&T. For the stock numbers, we get an average force of 8543.82 Newtons. Here is our biggest problem, this doesn't take shifts into account, but the numbers should be relatively close. With the same force, 8543.82, you want the Mass needed for an acceleration of 6.89m/s/s. This comes out to be 2728.1 pounds, (or 1240kg for those who picked up that I was not mentioning some converting). 3430-2728=702lbs, quite a weight. Thats a 20% decrease in weight. The numbers desired, ignoring variables, could also be achieved by a 20% increase in horespower, probably a little more due to traction limitations, but this would have to be accross the board.

For those who didn't read through, roughly 700 pounds would have to be removed to drop the 0-60mph time one second.