Help/advice tuning my first engine. N54

Bit of a backstory, I’ve never tuned anything before but i’ve watched nearly all of the courses available here. I picked up an ‘07 335i as a first tuning project car. Replaced the engine, car runs smooth, I added some larger turbo inlets, and I’m looking to tune it using MHD to flash and Tunerpro to modify the maps, in mostly stock form to get familiar with tuning it at a lower power level before I build a single turbo kit for the car. (It’s a DI, stock twins, vanos engine, probably not the best platform to start my tuning journey on, but I’m going to try my best)

Jumping in to tunerpro, I’m using a community built definition file, and I’m having a bit of trouble understanding the load axis being used here, as well as the number of maps available(I assumed there would be a large number of maps given the engine configuration). Is this just a bad definition file, or is this using load measurement I’m not familiar with? I’ve uploaded a picture of the main fuel and main ignition maps here.

Hopefully someone can give me some advice on getting started, looking at the datalogs I have (stock map, larger turbo inlets) the engine is running a bit lean and my stft’s are going up to as high as 18% at higher load so I’m not driving the car much till I get this figured out. Any advice is appreciated, I’ve looked through the forums here and can’t find much info on N54 tuning, or on using tunerpro(it is an open source software, so i know there’s not a huge amount of support for this software). Thanks in advance.

As a side note, I have replaced the factory msd80 with and msd81, and had everything bench flashed over so it’s all matching and works well. My datalogging software also show similiar load values to what’s listed on the tables here I’d just like to know what unit this is, and what tables i should be focusing on starting out, and what each one directly adjusts, as there’s 52 total fuel tables available…

What does the "community" that developed the maps say about the load axis -- is it load %? MAP in kPA? mass (of what) / (second or revolution)? What units does the data logging software indicate? Are you reading some OBD2 PID's (their units are defined -- see https://en.wikipedia.org/wiki/OBD-II_PIDs )

I found the link to a list of xdf files in a forum, with the title stating “this is a list of definition files for n54, etc” and all the reply’s were just other people saying how helpful they were and that they worked great, the forum was 5 years old.

I did find one result in a long list of google quick searches that said it was cylinder fill in milligrams per stroke, mg/stk, but nothing else confirming whether or not that’s true, though the numbers do seem close using that as a reference, do you think that’s it?

. The datalogging software is the exact same way, just saying “load actual - 145” for example, with no percentage by it, and no explanation though it’s consistent with the numbers on the load axis of these maps in tunerpro. My scan tool reads out load as 0-100% so not much help there as it’s different. And the forums i’ve spent hours reading though so far have been no help either. I did read through that link that you sent but I couldn’t really find an answer and was kind of difficult to grasp what it was saying.