So i want to turbo out my 04 cavalier, and i want to make sure i pass emissions too. So what do i need to do to keep it in the green, and what should i not do? Thanks a bunch.

Well since your in IL like me as long as you have access to hp tuners you will pass since we only have obd2 scan testing. That said, how much power are you looking to make, and what were you thinking bout ding for fueling?

Till i can get more money to beef up my engine, just low boost.

Boost doesn't matter, the size of the turbo does....a tiny t3 @12 psi is not the same as a GT3576R @12psi or an mp62 blower@12 psi regardless of pulley size. Stock eco can take quite a bit if you can dial th tune in. You should start at a rasonable power goal or quarter mile time and go from there. If your on a budget check into a sabb setup or even an lnf setup off a stock turbo cobalt or hhr.

Yea my goal now is 200HP then like 250HP, i want to go higher in the future when i can get more money. But yea thx i didn't know if messing with a turbo will effect my emission's.

With goals at roughly250 an mp62 blower setup would be easy and cheap if you piece it together. The Sabb setup wuld work well for you as well, do some searching on the saab setup and what you'll need.