RedMogT,
I have a GDI ( build week 24/15 )but I have not suffered the problem you have.
They all seem to rev up when first starting without touching the throttle and even with the ECU flash, there is still a short period of high revs which quickly settle down to around 1000/1100r.p.m whilst warming finally going down to 800r.p.m when warm.
It may well be worth going to your nearest dealer to see if the ECU flash has been done, it certainly improved my car no end.
