Does anyone know why the compression on a 250 hpdi vmax (6.0:1) is different than on the 200,225,&300 (6.2:1). I have checked the parts catalog and everything on a 225 and 250 look the same except for the ECU. Pistion are the same part number, heads, and head gaskets are the same part number and even the exhaust covers and gaskets are the same part number. and Reed valves are the same part number. My first guess was that the 250 had different pistons but like I said they are the same part number as the 225. Can the ECU control compression? We got any of the Hydrotec boys in here?