The 1996 to 1998 Porsche 911 (993) Turbo piston protrudes 5mm above the deck BY DESIGN at TDC.
This engine makes about 450 Bhp and 420 lb ft of torque from a 3.6 litre capacity. The Chamber design isn't disimilar to a Gen 2 Hemi (with some refinements).

This is done in order to reduce peak cylinder pressure load on the cylinder head gasket just after TDC.