Just bought a heatshield air intake

[serega12]

That's one of the resonators....

[petrified.rabbit]

actually, starting in some year (i originally thought 2009, but the new faced sedans might be as well and possibly all of them?) they advertised the first box in the tunnel as a post cat...

[serega12]

So they got two cats then? restriction x 2?

[Daox]

I bet the stock muffler is a bigger restriction than any modern CAT. They just don't cause restrictions.

[hammsaveo]

Doax, is there a better muffler for helping fuel econ...? Is there any reason to replace it for just that reason? Or will this only help with power? In turn using more fuel?

[Daox]

If you are driving to get good gas mileage (keeping rpms down), changing the muffler won't do anything for you. Its only when you are looking to get more power (airflow) through the muffler that it might become a restriction.

[hammsaveo]

That is what I thought same goes for the air filter situation..