Max boost xj220 and 220S

Can anyone tell me what the max boost on the xj220 and xj220S is (psi or bar)? I’ve read 1 bar in one place, and 25psi (almost 2 bar) somewhere else. I believe engine internals are the same for both cars, is that true? The S cars didn’t get stuff like titanium conrods and lightweight pistons and different crank?
Don’t have my technical manuals yet.