“Believe it or not, weight isn’t much of a factor in top speed, though it does affect acceleration. Ask anyone who’s built a car to run at Bonneville.”
I remember one record setting car that had a huge load of dry ice on board to for cooling. The weight was less of a handicap than the drag from ducting cooling air would have been.
I also remember Car & Driver doing a top speed test of several cars at the Transportation Research Center near the end of the 1980’s. One of them was a heavily modified Callaway Corvette, and in order to keep the rear end planted they had 200 pounds of sand bags in the rear hatch.
C4 Corvettes are known for rear end lift at high speeds, and for a top speed run this was probably the best solution.