Editing system filament presets is a PITA
So the shrinkage compensation system preset of 0.18% for Prusament PC Blend is off enough that my parts are not accurate. I can change this of course but then I have to save this as a user preset. This is super annoying because I have to save one for each nozzle type since the max volumetric flows will be different. I can edit the appropriate section (which was hard to find) in cache/PrusaResearch.ini but that will get overwritten on the next update. Wish there was a better way to overlay user specific changes on top of system presets without having to save it as a new instance. Hopefully this gets fixed in PrusaSlicer 3.0.
This is also a reason why one shouldn't blindly trust the Prusa supplied presets.
RE: Editing system filament presets is a PITA
You xan make PR to their repo to have tte change permanent. If they accept it is another story....
See my GitHub and printables.com for some 3d stuff that you may like.