setup is priority when upping boost pressure. could be a boost hose collapsing, boost cut as tony has indicated the chip DOES have a boost cut. sometimes a lean engine will miss fire. I would refrain from driving it hard/on boost until its been setup and checked out. going from 8psi to over a bar is a massive jump, mfi cant fuel for both ends of the spectrum. as mine stands it is on the lean side at 10 psi but fuels perfectly at a bar of boost. and tbh a bar is about the most mfi can fuel for. setting up is a bit of a guessing game and only a experienced tuner should really set these cars up