The distance from the piston pin the the top of the piston is the compression height. That is different between the 790 and 865 to maintain the same compression ratio. That would be MUCH cheaper to change than changing the combustion chamber on the cylinder head, in the long run.
I have a question. What is a "safe" static compression ratio to run on crap fuel, like 87 octane? Also, would would the "recommended" minimum octane be for these new TTP pistons?
