[Schwarzeritter]

[I]
Unfortunetly you really on these cars get what you pay for.
I would tell you do nothing then too risk your engine with poor tuning, often these backyard or junkyard mechanics typically dont take into consideration that Porsche like most makers take huge sums of time ensuring that the car gives you huge performance along with longevity.

I used do deal with Japanese cars and over the years I would get tired of kids who simply wont pay for quality, you end up with a poorly engineerd piece of software that has a crap interface too its hardware along with this there ( practically jimmy rigged ) so that they manipulate the sensors rather than recalibrated via DME/ECU open source tuning.

Point in case GIAC is a good start. Or maybe just take that starbucks coffee money that we all spent and place that all aside in a little box that says make my Porsche go-go-go.
I promise you the money even in economic hard times suddenly and not magically appears before your eyes in this box =)

Point in case is : Your tuning is only as good as your Tuner & the software is only as good as the software programe writer, along with this goes into the hardware engineer who had too make it interface.