The short answer is you can do it, but it won't be easy.
On the hardware side if you change the IAP (inlet air pressure) sensor you will need to also replace the SAP (static air pressure) sensor. Both need to have the same voltage to pressure output. One of the first things the software does is subtract the SAP from the IAP to establish absolute pressure. You can't be comparing apples and oranges.
On the software side it may be more involved than just tweaking the maps. The variables are limited to 16 bit numbers meaning 0-65,535 or -32,767 to + 32,767. (I've seen no evidence yet of any floating point math taking place) So if the current formula is ranged around -32,767 being vacum or -1 atmosphere and 0 being 1 atmosphere or ambient which makes 32,767 2 atmosphere. That would make 3 atmosphere out of range of a 16 bit variable. That means you would have to go through the code and rescale all the related variables. It would mean rewriting, and worse, recompiling the code.
Imagine you've just been handed a thousand page manuscript on paper, you don't have the word processor file. You boss wants you to go through it and change a character's name from Fred to Mike. While that would be a pain you could still do it without retyping the entire thing. Just whiteout Fred and type in Mike. They are both four characters long. This is also easy to do in the ECU software, replace one byte of code/data with a different byte of code/data. If the software says compare something to 6 I can change it to 3.
But what if your boss wants you to change the characters name to Helen? Helen doesn't fit in place of Fred. Not only that Helen is female and now you have to find every reference to 'he' and change it so 'she' etc. That is what you are asking when you want to go to 3 atmospheres. Not impossible, but not in the same league as just tweaking some map numbers.
To continue the analogy; without the original Word file (source code) you will have to retype (compile) the entire manuscript by hand. The obvious answer would be to scan the manuscript and create a new word file (disassemble the code and create a new assembly source code. ) Easier than doing it by hand but still time consuming.
The IDApro software we are using to disassemble the code should allow us to do this, in theory, but I haven't tried it yet.
