Milling a set of TRW 13.5:1 Pistons

Depends on if the dome is hollow or not. I am sure you could have enough cut off to get it down to 11.5 or more. You need to find out the dome volume, your exact head cc, what compression you are shooting for, etc. I would probably re-sell them and get what you need.

Or, do an E85 engine. lol