What a great topic

The EMFPR on the Bosch KE system is a global modifier.
When you increase the pressure you increase it everywhere.

The problem you run into, is the point where you have to decide, where do we go from here? You can have more power and terrible economy, along with the other side effects of excessive fuelling, or you can find ways to add supplementary fuel.

I personally advise customers to go for the additional fuel supply injectors or better management so as to maintain off power economy and maximum engine longevity.

The 2 types of controller available are quite different in their properties. mappable and fixed. The fixed type is used primarily where we require a nice midrange spike but dont want to up teh whole pressure system to cope with that boost. In this scenario i will set the boost to say, 22peak and 16held. For this, the fixed injector will switch on at 17psi and fuel for the 22. That way the system can be left to cope wth the power produced by 16psi, and still make good midrange torque through the spike.

The mappable injector has already been nicely covered

Please all take note:
Boost pressure means nothing. Airflow is all that counts as far as fuelling goes. Even a worn camshaft can make the difference between 22psi and 16psi making the same horsepower. Big Boost just means for some reason the air you require cant get into teh cylinder easily and you possibly could be spending your money better elsewhere.

Hope this helps.