That's a lot of boost for just 340bhp.
Try to find out what fuel pump is on this car. Is it still the standard pump (in-tank)?

With all due respect, but have you got anything to compare it to? Do you have experience in driving a car with this kind of power?
I would seek assistance from somebody who knows what he's doing. Check the sensors for valid signals and measure compression. Then maybe put it on a rolling road to check.
But in the end I am afraid that you will be needing a new eprom to get it right.