I have an S13 SR20DET Blacktop (e5) wiring harness that has already been wired to work in an S13.
Used it for 2 years. When it was on a stock ECU, it ran perfectly fine, idled fine and everything.
Doesn’t look in the best condition due to splicing in of other electronics in the past but it works.
Guaranteed to start right up.
$150