Quote:
Originally Posted by wilsonp
Why don't aftermarket / HFCs have a pre-cat, then?
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Because...
pre-cats, or "pup" catalytic converters are there to reduce emissions before the catalytic converters heat up. The down stream 02 sensors aren't heated up and working at this point, either, so it wont throw a CEL if they are missing, and noone (meaning not me) really gives a **** about preventing the tiny bit of pollution experienced before the main cats achieve light off, and eliminating them reduces restriction to flow.