Though this subject has been touched upon in other forums, I think it maybe important to have it's own string: CR.
Cobb makes a short block with an 11:1 CR. It is very expensive at $4500 not including core charge. I doubt this is very streetable.
Techworks Engineering makes a 10.2:1 piston, which is a slight bump. What is great about this piston is it's assymetrical dish, which better corresponds to the flame front of combustion. This supposedly improves detonation resistance and increases horsepower.
Three issues are: Engine Management, detonation, and emissions.
Engine management: what requirements does raising the CR incur, if any.
Detonation: As the Phase II EJ25 runs 10:1 on 87 RON, I don't see why it can't run 10.2:1 or even 11:1 on 92 RON. However, it is still a valid question.
Emissions: As you raise the squish, so too you raise the NOx emissions as well as sulfuric emissions. How does this effect the car's capability to pass a smog test? Here in Alaska, according to my local E/M station, NOx emissions are not tested. It varies from state to state.
With intake, Cobb heads & camshafts, headers, exhaust, & ignition, I believe raising the Compression ratio and installing Pauter rods are the steps necessary for me to obtain my goal of 215 HP at the crank NA.
All of your thoughts will be appreciated