If I remember well, raising fuel pressure of the KE-Jetronic will deliver about 5-7% more fuel throughout the rev range, so fuel comsumption will rise with that one.

You can buy an (adjustable) switch, which is pressure sensitive and could start the cold start injector at a certain boost level.

To be able to check how the engine runs, one could opt to mount a lambda sensor in the exhaust and connect it to an air/fuel gauge. Then you will always know if the engine runs lean, rich or "normal". Could be very interesting in case of tuning plans

Cheers