Mastai Ferretti Shirts: Preshrunk?

Not in general I don't think - you may get some shrinkage with some of the shirts.

+1 they're not as high level.

I have experienced shrinkage with some of the Saitt SpA shirts. Most notably, the Agho brand.

I have a couple casual MF shirts. They look a bit vintage, no idea if preshrunk, pretty slim fit. Quality is average, but fine for me for summer (not for office). Price in Italy is much cheaper than Barba, Borrelli, Finamore, Lorenzini, same for quality.

I doubt the shirts are pre-shrunk.
fabric is sanforized. this means shrinkage is reduced to 1.5-3%
high end fabrics with very tight constructions should shrink less the lower priced fabrics.

but some better twill fabrics will stretch in the sleeves, if put through a commercial laundry with automated pressing equipment