I read about 6 threads comparing mid lengths to other sized headers, but none of them answered my question. Also, the pace setter headers I am eyeing also say that they will not fit vehicles with A.I.R. What is A.I.R.? I probably know but am not familiar with that acronym.

 

They are emissions legal if they have a CARB-EO number and a plate with that number tack welded to the headers. Several popular brands have the CARB certification. AT least for the V8's.... not sure about the V6's.

AIR is the air injection system. On the LT1's, there's a small electric vane-type pump that blows air into the exhaust system on startup. The air helps burn the rich startup mixture in the exhaust system, to help the cats heat up faster. They don't work unless they are hot. Not sure exactly what the system looks like on the V6, but it should be similar.

 

As long as they have emissions fittings they are legal since they don't relocate the CAT.

 

On the LS1 anything other then a shorty has to relocate the cat. I have mids with emission hook ups and they still move the cats. They aren't legal technically but I was able to pass smog with them on, possible to fail visual though.

I have seen shorties claimed to be legal mids. Might be different with the V6 though since stock the cat is moved back further then the V8s. As Injuneer said, look for a CARB number.

 

if you have cats and less less than 5000 miles per year they are legal also.

 

I looked more thoroghly, and they say they have "1 - Flanged collector.
3 - Hookups for smog and engine management sensors.
6 - Comes with header extension to connect to stock system. Fabrication may be required."

So it should fit, because I'm fairly sure I don't have A.I.R.

So am I to understand that mid lengths give slightly more power than shortys? I'm hoping to get mostly low end power.

 

Shorties give little gain. Mids are closer to long tubes as far as gains.