Quote:
Originally Posted by jahsoul
For me, it's less about seeing HJS as the end all, as much as it is being a cat that doesn't throw any CELs, unless things have gotten better over the past few years in that regards. Also, for me, the downpipe being double walled is a benefit for what I'm going for. Does the VRSF downpipes throw codes?
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I assume your car is going to be tuned with something like MHD? If that is true, MHD supresses the check engine light for catalyst efficiency codes. The only time this is an issue is if you live in a place that requires smog checks where they are actually scanning the car for monitor readiness. The CAT monitors will just never be "Ready".
I don't really see how an HJS cat would prevent the check engine codes from illuminating if you have no tune, since in theory they have a lower cell count catalyst, and these E90s are extremely finicky with catalyst efficiency.
Based on my research even the HJS cats will still fail smog checks and set codes, especially since they tend to be around the ~200-300cpsi where an OE cat is like 600-800cpsi. States like California still list the HJS cats as "Offroad only use" since they don't meet emissions standards.