Dude.. you still haven't told me who is mapping it? Plus you need a fuel pump and injectors for the VF35 turbo. It's the same turbo I have.. you will also need an intercooler. Did you buy a decat uppipe as well as the downpipe, centre cat and back 2 sections? Even for the remap on the standard turbo you need a fuel pump ,walboro preferably. And with an upgraded intercooler (top mount anyways) you will need the bigger scoop and undertray etc.
I feel like you've missed a few vital things here..have you even had the car checked properly for the poor running or just decided yourself about the downpipe leak causing the problems? Sorry.. but I'm just a bit dubious!