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These are calculated potential speeds for gearing evaluation purposes only.

They do not imply that your engine will run as low as 1500 rpm or as fast as 7000 rpm

or that your car is capable of reaching the calculated speeds shown or that such speeds are safe

or that the tire size will fit your car.

The "Split" is the ratio of this gear to the previous gear.

The Split should be the same gear to gear or decrease slightly.

If the Split drops then increases as it does with some overdrive gears,

the gear will feel "too tall".

Rev/Mile is engine revolutions per mile, which is rpm at 60 mph.

The standards for the Superformance Mk III are:
Transmission: Tremec 3550/TKO 5-speed (0.68 5th)
Rear Axle Ratio: 3.73 prior to 2068, 3.46 from 2068 on.
Rear Tire Size: 275/60-15

The standards for the Superformance Brock Coupe are:
Transmission: Tremec T-56 6-speed (Mustang SVT)
Rear Axle Ratio: 3.46
Rear Tire Size: 285/50-18

The standards for the Superformance GT are:
Transmission: RBT 5-speed (transaxle)
Rear Axle Ratio: 3.77.
Rear Tire Size: 275/60-15
or
Transmission: Ford GT Transaxle (6-speed)
Rear Axle Ratio: 3.36

The 3.46 and 3.91 rear axle ratios are for the Coupe and Mk III from 2068 on..
The 3.77 rear axle ratio is for the GT.
The others are for the Mk III prior to 2068.