I was reading on another thread about the Thorley Header being "Approved" for emissions and others not. I live where we dont have to worry about this, but it got me thinking.

What is the difference in an "Approved" header and a "non approved" header. Whad difference does it make if you still pass the exhaust output test?

I'm betting that it's some kind of BS where Thorley paid some government agency to say it was approved and the others did not. Because I cant see how putting a header on, with all the sensors still intact could make the output much worse than stock. Not to mention, make it worse that a 250-300 HP V8 :-/

Confused,
Zig

I'm betting that it's some kind of BS where Thorley paid some government agency to say it was approved and the others did not.

I think that's pretty much the gist of it.  It takes a few tens of thousands of dollars (I think) to get a part CARB tested & approved.

It's unfortunate that what comes out of the pipe only matters if it fails and that if you pass the emissions you can still fail the visual

It might have the o2 sensor bung and the others don't? And it doesn't matter what size engine you have they all have different requirements for emmision levels. They put in your VIN number and a set of standards automatically comes up on the computer and you have to be within those standards.
They got mostly young guys at the test stations here and they glance under the hood to make sure everything is there and run the car on a wheel dyno if it passes your done,if it fails then they take a closer look.
Newer OBD2 cars just get plugged in under the dash and if the computer has no codes you pass.
At least thats how its done in Wisconsin.

 The other headers that I'm aware of have the o2 sensor bungs for the sammy and trackick. Why they wouldn't pass, I don't know. I've heard that the California Air Resource Board certification, a.k.a. the C.A.R.B. sticker, does cost a small fortune. I think that is why only Thorley has it. It's not like the Jeep crap, or anyone else's for that matter, that has to have air injection ports or anything like that. There is nothing special about the headers.
Where I live in Idaho, we go through the emissions testing once a year. I have never been failed because of the header. I have failed on unrelated matters like the cat was bad or the o2 sensor wasn't reading right, or the egr valve was shot. But not because of the header. And they will fail you because of a visual inspection here.

My guess is that the certification guarentees that it won't mess the fuelling up. The 02 sensor is switched out of circuit at idle and under power so unless the ECU was chipped a change of header design could screw the emissions.