Final update:
Took the car back to the first test facility this morning:
40KPH:
HC (ppm): 7 (limit 52) PASS
CO (%): 0.01 (limit 0.29) PASS
NO (ppm): 6 (limit 385) PASS
Curb Idle:
HC (ppm): 7 (limit 150) PASS
CO (%): 0.03 (limit 0.70) PASS
So the car now meets the emissions test and I can renew its plates. This was with the 93-octane tune and a 750RPM idle but most importantly, the factory H-pipe. I have to conclude that there's something up /wrong with the test facility that showed my NOx 10x the limit.