Originally Posted by m4a1mustang

The theoretical top speed for the 6MT 370 is 202 mph @ 7500 RPM. (275/35/19 tire, 3.692 final gear ratio, .794 6th gear ratio).

In stock form with the limiter removed the car is drag limited to around 165-168 mph in perfect conditions.

In 6th gear at 165 mph, you are at 6,100 rpm with the stock gearing. 5th at 7500 rpm will run up to 161 mph.

With a 4.08 final drive the theoretical top speed drops to 183 mph @ 7,500 rpm in 6th. At 165 mph in 6th gear you are at about 6750 rpm, though, so you are making more power in 6th at that speed than you were with the the factory gearing. Since you are making more power you will be able to overcome a little bit more drag, probably pushing your drag limited top speed up just a bit over stock gears.

The real gains with the 4.08 will be at normal speeds, though, since we aren't just out to do top speed runs. You'll get into the power band quicker.