We had three different tuners tune the PowerFC on the S15 - Rob @ Sabaddin, Sam @ Dr Drift & yourself. No-one got it right. You might remember the car - stock looking white jap-spec S15 - made 245rwkw. A bit's changed now though.
Now with the Nistune is runs like a factory car. Cold start is perfect, return to idle after backing off throttle is perfect. The car's also making more peak power on the same boost. Why was the PowerFC so bad? It used to idle hunt like crazy, cold start was terrible, return to idle was terrible. That's all gone. Unless it was just a 'bad' PowerFC, I would never go near one on an SR. That goes for all the DET-conversion Pulsars I've been around with PowerFC's as well, same rubbish idle.