I made some calculation on the compression ratio and the 11:1 seems accurate if piston to deck height remains unchanged (I'm not sure yet about this).

Assuming 10:1 is the exact stock compression ratio this gives a combustion chamber volume of 73,3 CC. The dome has a volume of approximately 7,8 CC.

659,73 cc + 65,5 cc / 65,5 cc = 11,07:1 CR