The ECU monitors the transmission mounted speed sensor to determine vehicle speed. When the vehicle speed limit is reached, the ECU cuts the fuel flow to the engine to slow the car.

The signal path for the vehicle speed sensor is as follows:

Sensor to Speedometer
Speedometer to ECU & Cruise Control

If the signal is interrupted at the actual connection to the ECU, speedometer, odometer and cruise control functions are preserved. The ECU does not receive a vehicle speed signal, therefore it will not limit the vehicle speed.

This modification is easy. But beware, it does include mutilation of the factory ECU wiring harness...not for the squeamish.

1.Disconnect negative battery terminal.
2.remove ECU cover from passenger side footwall.
3.Loosen bolt in center of main ECU connector.
4.Unplug main ECU connector.
5.Remove snap-on plastic cover from ECU connector.
6.Locate PINK wire with BLUE stripe. (this wire is located on the right half of the connector when plugged in)
7.Cut PINK/BLUE wire.
8.Reassemble ECU connection.
9.Reconnect negative battery terminal.
10.Drive 140mph.
 

This modification will cause the "check engine" light to illuminate. If you check the codes, you will get 0104 (Vehicle speed sensor fault) and 0504 (A/T control unit fault). So far there have been no drivability problems
associated with this mod.

Enjoy.

Credit: -Ben Garner