there is plenty of info in the web on just this subject

http://dsportmag.com/the-tech/boost-v ... -high-compression-ratios/

this for a start might yield some info.

as zigmondo said, if your going to mild boost on the street, keep it stock, particularly if you have a good motor to start with.

If you are rebuilding from scratch, you may want to drop it a little, but even then for the effort, its prob not worth it.

You can cheat and use two head gaskets to drop the compression a little.
maybe get a steel spacer cut.
those would have to be the cheapest ways to drop the compression a little for boost. After that its pistons and machining and expensive options.

If you lower compression (ie increase the combustion chamber size) it basically means you can jam more fuel and air mix into each pot and get more bang.

it helps with a few other things like detonation and heat management, but its all about cramming in more fuel and air.