Originally Posted by icase81
Not necessarily true.
I have to agree with you, only in that the devil is in the details. 1st. Please post a link to an appropriate "high quality metal substrate cat". I tried once before to find one and came up short. But the point was/is. Assume stock build. The D2.0 makes it's torque low in the RPM range. This negates somewhat the overall performance hit of the cat (low volume as you mentioned). Mount a header though, and you move the curve 2K upwards (to around 4500RPM), So now you trying to push a whole lot more volume, and it runs into the cat. So right when the benefits of the header should be coming in, there getting killed. Hence, A header (no cat) is worth about 7-10hp (real world), A header with a cat? Maybe 2-3HP? So it would prob be best to state that it is just not cost effective.