Hello
@lesh First, to add perspective, I purchased this early March of this year, so it is still very new. It took a minute to save up enough to get it. I don't regret that.
fpe (or regulator) I turned down the reg from default 130 bar to 100 bar for .22 (it will go back to 130 bar when I switch back to .357). I wasn't looking for fpe, I was looking for accuracy and thought that was a good starting point for .22 (and 130 bar is a good starting point for the .357 as it is factory default). That, coupled with again, the larger plenum pushing the .22 much better and also, to assist in reducing the bark when firing. I'm still trying to determine which pellet / slug it likes best as I have a limited number of different kinds. That quest will take me a minute as it takes time to gather different kinds. The reg will be adjusted once I find a pellet / slug it likes (probably going up in bar) to get fpe / distance without losing accuracy. This will take a minute also.
Barrel At purchase I got the 450mm subMOA barrel (which is standard for the 9mm, you just have to choose the length you want) as it is a solid steel barrel and supposedly, the best currently offered for the L2. In hindsight, I wish I would have gotten the 600mm barrel length. The reason is due to the shorter the barrel, the louder the bark. It's pretty loud. I do shoot in the backyard only because I have reasonable neighbors on each side. I don't know about my other neighbors as the neighborhood has several rental houses and they are always rotating renters in and out. So I'm guarded as to when I shoot and how much.
Jets As to the jets, I haven't messed with that yet. It still has the larger jets that are standard with the 9mm. I'm kind of hesitant on changing out the jets as like I said, the 9mm comes with a much larger plenum and reducing the jet size will just cause it to be slower in filling that plenum once the trigger is pulled. Other than filling the plenum faster, hence affect how quickly you can pull the trigger, it is unclear to me what changing the jets will do to the overall fpe / accuracy of the gun. Maybe you can enlighten me on that?
I think I've addressed everything... Let me know.