They told me that the tool to remove the regulator cost 650€. So, it's not easy for sure. And if you want maximum efficiency it's necessary to access the regulator severall times. To much hassle, at least for me.
According to Air Maks the regulator IS NOT accessible. I believe this model was designed for the UK market where most of airguns don't do more than 12FP, unless you have a FAC.
I almost bought a Krait Lite, but knowing that is not possible to access the regulator, I stepped back. To achieved maximum efficiency you need the tinkering with the regulator.