if someone wants to explain to me what a comp ratio is... i would love you. all i know is lower the comp ratio better for boost and higher comp ratio is good for n.a.
edit: but thank you patrick!
The compression ratio is a single number that can be used to predict the performance of any engine, particularly piston engines (but can be used on essentially any internal-combustion engine or external combustion engine as well).
In a piston engine it is the ratio between the volume of the cylinder and combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke.
Basically you want lower compression for a turbo becuase a turbo is adding in all that extra air into the combustion chamber and you need room for it.
A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass of air-fuel mixture due to its higher thermal efficiency. High ratios place the available oxygen and fuel molecules into a reduced space along with the adiabatic heat of compression - causing better mixing and evaporation of the fuel droplets. Thus they allow increased power at the moment of ignition and the extraction of more useful work from that power by expanding the hot gas to a greater degree.
Edit...you can do a high compression turbo motor...but you have to have a redicilious F*ckin tune becuase you are so much more prone to detonation and blowing up your motor