diffrent compression ratios can mean alot of things. lets start by saying this: turbo's push air into the engine, or rams it in. the more air you have, the more fuel you can burn, and the more power you will get.
now, if you increase the area that you are compressing in side the engine, you can compress more air, and make more power. you can do this in several ways. one easy way would be to get bigger head gasket. another way would be to bore out your engine. you can also get difrrent style pistons, or decrease the stroke of the engine (how far up the piston goes). that way, you can have more space to put in air and fuel.
PORTAMAN, please visit this website. it wont make you a turbo technecian, but it will point you in the right direction. (and you get nice pics too^ ^)
http://auto.howstuffworks.com/turbo.htm
reply once you see the page and let me know what you think (for future postings)