New FCON's are full stand alone, PFC F-CON is a piggy back fuel controller.
They are easy to set up, all you need is a EGT gauge to do it which you should always have anyway when modding any Starlet. I have full English instructions for installation and setup if needed, I gave these it Ian (Dub) and he uploaded to a FTP site I'm pretty sure.
Once you've set the base setting you can fine tune with the GCC on a dyno, you can also get the IPM (Injector Pulse Monitor) to see how your injectors are fairing meaning you can stay under 85% duty cycle. If running over 200hp you need bigger injectors, you can't increase the rail pressure as the HKS PFC F-CON is not meant to be used in conjunction with a aftermarket FPR, stock only as it confuses the unit.
The pre programmed ECU's in my opinion are too risky, yes you can sometimes get good results when using them in conjunction with a fuel controller or piggy back but if using one alone then it's massive gamble as 9/10 you don't know what they have been set for. The Japs run very odd maps sometimes, very rich and they use higher octane fuel. The conditions are very different out there and you never really know the full story behind it so my advice personally would be not to use one although everyone will be different and some do work out okay, just when spending £400.00 odd I like to know whats going on.
That's my take, by the way we got way over 200fly with a PFC F-CON using a K1 but that was with infinity boost way back in 2005, with an EGT gauge you can just back off and half throttle it without EGT gauges I would have probably blown ever Starlet engine I've had (Spec in the description)!:
http://uk.youtube.com/watch?v=4i8nnjQi4Eg