You definetly have a funny sounding problem. Although looking at fuel pump won't hurt (for information purposes) it's not really the problem as I understand it.
If you car was hitting fuel cut previously, running lower boost, it should do exactly the same now. Something is wrong and I wouldn't drive it on high boost until you have sorted it out.
1.34 bar is way beyond the fuel cut limit and beyond the safe operating capablility of the standard turbos. You should:
1. Check your pressure gauge tubing for blockages.
2. Fit the FCD you have.
3. Get a new restrictor ring.
4. Not drive at 1.34 bar on a standard fuel pump.