If that's the case, I'll leave the pistons alone . Turbo E320, I seen that pic of the modified head but come to think of it, since I'll be running less then 1 bar ( 14.5 psi) of boost (0.5 daily and maybe 0.8 - 0.9 at the strip ) I wondering if there is a need to modify anything at all. Maybe just smooth out the inward edge since sharp edges help detonation .

__________________
190E 3.0-24v (M104 980) turbo @ 0.8 bar
1/4 mile: 2.483 / 13.540 / 175.17 km/h (street tires)