Custom exhaust?

[Sammy]

Has anyone thought about/done a custom exhaust for their car? In reading all the posts about headers I am interested but not at the cost of not passing emissions. I think it is Fabspeed that has the headers with the "high flow" cats but they cost an arm and a leg. What about picking up a set of headers (without the cats) and having a muffler shop weld in "high flow" cats and an O2 bung (where the secondary cats are located) so that you get the benefit of better headers but also have a set of "primary" cats? Or are the secondary cats the same as the primary cats? Or should I just stick in new headers (still have a bung welded in after the secondary cats) and go from there?

I know nuttin' bout catamalytic converter dezine...

Forgive me as there is plenty of information using the search function but not quite the same as what I'm thinking about...

[Topless]

Originally Posted by Sammy

Has anyone thought about/done a custom exhaust for their car? In reading all the posts about headers I am interested but not at the cost of not passing emissions. I think it is Fabspeed that has the headers with the "high flow" cats but they cost an arm and a leg. What about picking up a set of headers (without the cats) and having a muffler shop weld in "high flow" cats and an O2 bung (where the secondary cats are located) so that you get the benefit of better headers but also have a set of "primary" cats? Or are the secondary cats the same as the primary cats? Or should I just stick in new headers (still have a bung welded in after the secondary cats) and go from there?

I know nuttin' bout catamalytic converter dezine...

Forgive me as there is plenty of information using the search function but not quite the same as what I'm thinking about...

Sammy,
I think you are on to something here. This would be the best way to get improved performance from a good set of headers without the downside of tuning issues, emission test issues, CEL issues etc. I just don't know anyone who has done it yet though.

[Cloudsurfer]

Great idea, difficult to implement. If you look at all the non-catted headers out there (TurboWerx, B&B, SuperSprint, the Chinese copies) and compare them to the catted headers from FabSpeed, you'll notice significant design differences to accommodate the cat in the length of the primaries. I don't think there is any way to make room for a cat in any of the manufactured non catted headers.

I have heard that Nello at MaxSpeed will soon have high flow catted headers, but I cannot verify this. Aside from that, I think you'd be designing an building a complete header from the ground up if you wanted to do this.

In terms of performance and avoiding CELs, you can run a non catted header, and relocate the secondary O2 sensors to after the secondary (well now your only) cats.

Hope this helps

Patrick

[Sammy]

Originally Posted by bmwm750

Great idea, difficult to implement. If you look at all the non-catted headers out there (TurboWerx, B&B, SuperSprint, the Chinese copies) and compare them to the catted headers from FabSpeed, you'll notice significant design differences to accommodate the cat in the length of the primaries. I don't think there is any way to make room for a cat in any of the manufactured non catted headers.

I have heard that Nello at MaxSpeed will soon have high flow catted headers, but I cannot verify this. Aside from that, I think you'd be designing an building a complete header from the ground up if you wanted to do this.

In terms of performance and avoiding CELs, you can run a non catted header, and relocate the secondary O2 sensors to after the secondary (well now your only) cats.

Hope this helps

Patrick

I was thinking the secondary cats are not quite up to par in terms of emissions performance with the primary cats. I was looking to simply swap out better cats in place of the secondary cats if it made sense?