The 4.8 does not have a speed limiter, provided the top speed is not redline in final drive gear, top speed would not be lost (engine will spin to a higher rpm with 4:10 gearing, due to lower gear vs unchanged aero drag).

A vehicle with a speed limiter would have a lower top speed.

The 4.8 will launch harder and accelerate faster with the lower gearing (better 0 to 60, 0 to 100 and 1/4 mile times).

The sensors in the BMW monitor trans input & output shaft relative speed, the wheel sensors measure wheel to wheel relative speed and the TC transfer torque front/rear.

The sensors do not monitor trans & TC speed relative to wheel speed.

Lower gearing WILL work in the application.

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'03 X5 4.4 Sport, last of the M62s (8-03 build date)
I believe in deadication to craftmanship in a world of mediocrity!