I recently decided to switch from the stock P59 PCM to the Terminator X ECU. I ordered the kit for an Ls1 but since my car is an LT1 this required some minor wiring changes. After extending the cam and crank harnesses the Holley plugged right into the Torq head sensors I was already using, I also had to extend the knock sensor harness and swap the TPS and IAC to the other side of the intake. I ran the ignition, ground and fuel pump wires to the stock pins in the factory harness still in the car so the new harness can be removed as easily as the original. After setting up the parameters in the handheld the car fired right up and after some minor adjustments to the throttle screw the car ran and drove great!
I also installed the Holley Digital dash with a custom 3d printed bezel and the programmable led light bar. I wired the turn signals and fuel level gauge through the I/O harness and everything works great! I recently got the car back on the dyno and picked up an average of 20 horse power over the factory GM computer.