Mapping and Boost levels???

[L18M]

i might have missed something but am having trouble trying to get my head around mapping and boost levels.
(bear with me, i think this will be a long one)
im coming up to a situation where i\'m gonna mod my fc quite a bit, larger tub, ext wastegate, injectors, pfc, boost controler on its way etc... and was thinking if:

a) i should just fit the pfc for now n drive it on base map (with no boost controller) for a bit then take to be mapped and install tub later on once i finish collecting all my parts (no boost controller)

b) as above but with boost controller for the latter part

i understand the pfc can be mapped without boost controller at which the max boost pressure will be the spring rate of the wastegate. but what if you add a boost controller on at a later date? would the car need to be mapped again for running higher boost pressure?
surely if the map was for spring rate pressure then if the boost is increased the map would not be able to compensate for higher boost?

if you map the car at 1.3bar on the boost controller but later turn down the boost (or even turn off the boost controller) then would that mean the car would be running rich?

i dont quite understand how one map (say mapped for .6bar) can be used for 1.3bar boost?
or does the ecu work its magic and compensate for this?

sorry if these are stupid questions!
the reason for asking is to see if it would be better to run my fc on base map pfc or just keep stock ecu with fcd until i get everything sorted to fit tub etc then install pfc and properly mapped and if boost controller is required (preffered) to install prior to car being mapped.

many thanks in advance
(ps yes i know i should of got boost controller 1st before playing with pfc etc.. should learn to walk before learning to run. just a bad habit of mind :evillaugh)

[grinder]

i think the initial map is the expensive but - so if you do fit the boost controller after the PFC - it might only cost you say £100 to have it redone

[Prof]

Mapping -
 
If you Map for a given amount of boost pressure, then you can run anything up to that pressure - as the person doing the mapping should have configured all the correct fuelling for the cells in between.
 
So if you Map for 1.2 BAR, then run around at 0.9 BAR most of the time because you turn down the boost controller - there would be no need to remap.
 
A base map is just that - its a map that\'s designed just to get the engine running - it will be driveable off boost, but will most likely be setup to overfuel on boost to protect the engine and make it bog - forcing you to let of the gas pedal a little.  The reason for doing this is that mapping of the ECU will need to be done for the specific setup on your car - the mix of exhaust / intake / intercooler / injectors etc. will need to be tuned for and it varies from engine to engine - even with similar mods.  The tuner will probably have maps that have some of your specific changes, so he can start with an already built map that can be tweaked.
 
Hope that helps...

[L18M]

thats great prof (esp the 2nd paragraph)
so if a car is on stock ecu then you turn up the boost from stock 6psi to 12psi then im assuming it will prob run lean?