Quote:
Originally posted by oab_au
The third cat can not act as a resonator, there has to be a large volume for the gas to expand into and the cat is full of a ceramic honeycomb. The resonator is full of nothing, this is where the gas pressure is disapated.
Its effectiveness is related to the speed of the engine, not much at low rpms 2k to 3k, most important 4k up, overtaking power will suffer.
Harvey.
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The third cat in the US models has cat material in the center and then fairly open volume area forward and rear of the cat material.
I understand what you're saying with regard to overtaking power, but it hasn't been my experience with my own car that that is the case. Obviously it's hard to know without dyno plots but the car doesn't seem any slower.