ok you deffinately need to read the turbo 101 and turbo vs supercharger threads at the top of this forum.
also check
www.howstuffworks.com and find out how a turbo works and what it does.
a less restrictive exhaust system means you want a big exhaust pipe like 2 1/2 or 3 inch in diameter from the turbo back and if you want to be legal you should put a cat and muffler on there too but try to get those the same size as the exhaust pipe. this will allow the exhaust gas to out of the turbo faster and therefore spool faster. you also want to put a less restrictive intake, i have found that a pvc pipe and an intake from the import isle at autozone work fine.