I have a couple of questions. Since my ported 13B GSL-SE motor with Holley Carburetor setup was recently stolen, I am forced to move forward with my Turbo FB project.

I have a complete S4 Motor and Drivetrain. I already understand that I could use the wire harness and ecu from the S4 as well to get started. Before I research and source these items.

Could I use the S5 Harness and ecu on the S4 motor?

 

Nope.
the s5 harness has an electric OMP setup that in essence talks to the ECU where as the S4 engine has a mechanical OMP.NO electrical connection is needed to run a Mechanical OMP.
The air Flow meters are different,the ECU is Different,the TPS is different

Shall I go on?

 

No need. I understand. Thank you very much.