Your car has a mechanical differential.
If you change your diff gearing, you change your final drive ratio...going to a numerically higher diff will improve your 0-60 time, but you'll increase RPMS at all speeds, so can be buzzy on the highway.
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car