Damn, No one helped you barstewards
Ive an engine to get on with stripping so il make this more brief than i maybe would have done last night had i not fell asleep

There are various ways of introducing a controlled boost pressure increase above the base actuator level (IE actuator preload level) and the main 2 are:

Bleed Off & Bleed on.

Bleed Off:
This is what an Amal valve does. It bleeds a set amount from the original boost signal via the "R" port in a 3port system or via the outlet port on a 2 port system. Either way, it controls an air leak on the actuator - compressor pipe, thus raising the boost level. This can be mapped in fashion by altering numbers in the boost map so that the valve is pulsated at a set frequency which we can vary slightly with RPM. What we cannot do, is set any real boost curve using this primitive method.

Bleed On:
This is what Air Injectors do.
This sytem usually uses a totally closed system so the compressor signal pressure is at the intake end of an injector or 2 and the wastegate pipe is at the nozzle end. This way, the amount we pulse the injectors will vary the amount of air that reaches the wastegate. Due to the way this system works we can ensure that no pressure at all reaches teh gate until we want it to, thus ensuring as rapid a spool up as the turbo can give us, presuming no excess turbine housing pressure causes wastegate creep. One of teh main benefits is teh fact once we have started to rev the engine and our boost begins to tail off naturally, we can virtually close the wastegate if required and force the turbo to give us every last ounce of boost it can, should of course we wish to do this. The system is far more mappable due to the finite adjustment an injector nozzle has in relation to a simple solenoid that is the Amal valve.

Important:
Remember that Bleed on and Bleed off are technically electrical inversions of each other so the system needs to have the boost map control inverted to use one or teh other. IE: Fully open max boost in an amal valve map would give no boost on an AI map. To alter this you have to either:

1) Use an AI Inverter such as we manufacture & use. (L1, L6 or L8)
2) Run Pectel hardware/software which will enable this if required. (L8 or P8 only)

I hope this has helped.