I've got an S5 TII engine pulled from a '90 RX7 that I want to put into my truck, only problem is I don't have the wiring harness or ECU. I've read that you can use the wiring harness from an N/A, which I have.

The wiring harness I have is pulled from an '86 N/A though, so will the fact that it is from an S4 make any difference, or will that still work together fine?

Also, I'm planning on upgrading the turbo, the exhaust will be a full 3" all the way through, it will have a bigger custom intake, and a front mount intercooler; so with these few little mods would getting a stand alone EMS and just skipping out on the stock ECU be worth it? What else would I need if I were to go with an aftermarket computer like a Haltech or Apexi PFC?

Also, if anyone has the computer from an S5 TII... let me know.

 

You will want to use a S5 n/a or T2 harness. S4 n/a harness has different connectors and I believe there are more wires in the S5 harness as well.