For smaller GA engines, not a problem.
Even the turbosupercharged ones have absolute pressure controllers to regulate the total turbo/engine output...provided of course that the operating pilot is smart enough to have the oil nice and warm before pushing the throttles up.
With large supercharged radial engines, on a very cold day, often times the BMEP will be the limiting factor, rather than manifold pressure.
All the pilot has to do is be able to actually read the gauge accurately.