Following the installation of the HPA high pressure fuel pump (HPFP) the GTI became slower to start with the engine turning over longer before catching.
A data log of the fuel rail pressure versus set point during a third gear pull at 26 psi of boost was also recorded:
The fuel rail pressure well below the set point was another indication that something was not right.
HPA had me return the fuel pump and about a week later after being serviced it was returned.
At this point the HPFP checked out good.