all the above info is correct, but ill just reiterate it in another way
you can use both High and Low compression with boost. Low compression just allows for more boost to be shoved in the motor, as well as more mistakes you can make. High compression really needs to be tuned perfectly to prevent any detonation. also, the higher the compression, the less boost you can run.
you will yeild better power in off boost areas with higher compression, but your top end wont be as high. its better for an all around power curve.
you will yield better peak power with low compression, but it will be peaky (very small powerband, as opposed to high compressions wide powerband)
seeing as you are pretty new to the whole scene, i would say research research research. and then when you think you know it all, research some more before you do anything.
if i would have researched more, i would have bought some different parts, and gotten other parts cheaper.
and 8psi will be fine with stock engine if tuned right. my friends boost their stock motors to 14 psi. though they fabricate turbo kits for a living, so they know exactly what they are doing.
once again:
Low Comp: more boost, more peak power, less tuning needed
High Comp: less boost, broad powerband, lots and lots of tuning needed
which you choose is up to you
