Hi ultra,

our catalogue only shows the basic dimensions, hence the pistons appear identical. However, the piston crowns are slightly different designs albeit difficult to tell even if you compare the two pistons side by side. I have an advantage of the the original cad drawings to refer to...

You want the 9.5:compression ratio piston, from memory this is 013 38 xx (xx denotes piston size).

Regards,

MAHLE UK