I started doing something like this but with laps of Daytona instead of pure top speed on Sarthe. Also I didn't change tires. Then I decided it was like comparing apples to oranges if you didn't have the same tires but I didn't want to buy 6-8000 CR tires for 1000+ cars so I kind of gave up. Now I wonder if tires would make much difference on a long straight like Sarthe? I need to do some experimenting...
Next thing to think about. Do you give 20K CR trannys to every car, every car that hits the rev limiter, or none (effectively limiting a group of cars to a lower top speed than they are capable of - think early muscle cars)?