2l8uburn,
All you need to make an engine run is Air,Spark & Fuel. Right?When you alter those three combinations to increase cylinder pressure you are adding HP & torque. You can do it with a chip, by changing the air /fuel ratio and engine timing. Forced air induction (SC or Turbo) and N20.

When you increase cylinder pressure you are creating a larger more efficient combustion in the cylinder. As this happens you also increase the energy that is released from the combustion to push the piston down. This increased energy adds more stress to the piston,rod and crank asy's. The additional pressure of air being forced on the piston from the supercharger adds to the cylinder pressure also. That's why I've been saying a certain combination is pushing the rods to the breaking point.

any mod that increase hp, increase cylinder pressure. How much each mod increases the cylinder pressure is anyones guess. I don't have a dyno & Lightning engines lying around to install cylinder head pressure transducers to do a mod by mod break-down. That's what it would take to accuratly determine the amount of cylinder pressure the rods and heads can take. Hope this helped!