so its illegal ok great. there are inspections to make sure you fallow the law, fine. these inspections then fail to find my modifications??? im still breaking the law sure but like what exactly am i doing wrong here? if i find an exhaust system that perfectly mimics the ratios of gases that stock has then so what? it shouldn't effect mpg much as the power gains are under boost, the car should perform exactly the same when cruising as when stock right?
also what does ATR stand for?
You're talking about STATE inspections, which have different requirements on a county by county basis. There are a lot of situations where a thing may be legal in your state, but not legal federally (as in the entire country). Take marijuana for example.. there are several states which have legalized it, you can buy it in stores, yet it's still illegal in all 50 states under federal law. A lot of these sorts of things come down to enforcement. If it's legal in your state, then state/county/municipal law enforcement isn't going to bother you about it.. and it's HIGHLY unlikely that someone in Washington D.C. is going to send out U.S. Marshals to arrest you for tampering with emissions related equipment on your vehicle.
As far as what you're doing wrong (other than being a straight up criminal with no regard to the law

), all of those things you have mentioned are designed to reduce the emissions of your vehicle. Getting rid of them will end up damaging the environment slightly more than if you left them alone (aside from potentially the tune.. it would probably be possible to retune the car to where it had even less emissions than stock.. the stock tune is made to work for all cars in all environments, so there are a lot of things sacrificed to make that work). And like XJ said, if you put on a different exhaust that's identical to the stock exhaust, you might as well have just left the stock exhaust on there because it's not going to be any different.
ATR stands for Access Tuner Race.. that's the computer software you can use to edit tunes on your Access Port, log WBO2 data, and view learning values stored in the ECU, among other things.
the new parts would flow more freely while still being capable of the same levels of filtration stock is.
You're talking about something that doesn't exist.