Significantly more, which is why the blanket statement banded around by people of "no more than 1.4bar on pump fuel" seems very odd to me.
It depends on turbo, cams, static comp ratio, cam timing, gasket thickness, deck height, squish, piston cooling, coatings, fuelling, ign timing and spark energy, intercooling, manifold and turbine housing sizing, water injection.....to mention just a few things.
It's not the extra pressure rise (say 35psi max) over the combustion pressure but the related issues of all the extra airflow being pumped through the motor that is the issue.
Someone may be able to run 1.6bar all day long on Optimax, someone else running a different setup and even a LOWER compression ratio (if other things are not correct) may det at anything over 1.2bar. It all depends on the individual setup.
My 0.02p worth.
Choose a skilled mapper who you trust!