[jahsoul]

I hope all is well. I've been searching for an answer to this and haven't been able to find it, so I don't mind if anyone can point me in the right direction if this questions has already been asked and answered, but I'm looking to have my OEM downpipes modified to add HJS cats. I know they are double walled, but I was wondering if anyone has ventured to perform this. Thanks in advance for any response.

[lookalikehuuh]

I assume you want the HJS cats for higher flow correct as compared to OE cats?

[jahsoul]

Originally Posted by lookalikehuuh

I assume you want the HJS cats for higher flow correct as compared to OE cats?

This is exactly what I'm hoping for. Honestly, because of how they built these parts for heat retention, I'm sticking with an OE style turbo but really want to keep the OEM downpipes and just modify the cats on them. Flex section + double walled cat + upgraded cats would be perfect....(for me, at least..lol)

[lookalikehuuh]

That seems like a crazy amount of work to do for not much gain when there are good options out there. I personally have the VRSF high flow catted DPs, and they have worked great for the past 5 years. My car is tuned on E50 pushing 20PSI on stock turbos so kind of pushing the limit of the stockies with my setup.

No smell or anything else like catless DPs do. Fitment was spot on, and they were easy to install.

It could just be me, but HJS doesn't seem to be the end all be all of cats or anything other than fabspeed pushing them like crazy since its apparently they brand they carry. On other forums though people seem to be mixed about them.

[jahsoul]

Originally Posted by lookalikehuuh

That seems like a crazy amount of work to do for not much gain when there are good options out there. I personally have the VRSF high flow catted DPs, and they have worked great for the past 5 years. My car is tuned on E50 pushing 20PSI on stock turbos so kind of pushing the limit of the stockies with my setup.

No smell or anything else like catless DPs do. Fitment was spot on, and they were easy to install.

It could just be me, but HJS doesn't seem to be the end all be all of cats or anything other than fabspeed pushing them like crazy since its apparently they brand they carry. On other forums though people seem to be mixed about them.

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?

[lookalikehuuh]

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?

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.

[jahsoul]

Originally Posted by lookalikehuuh

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.

I've read the opposite and saw that HJS were the only ones that didn't pop the CEL because of the Euro4+/TUV certificiation. I might be wrong though.. *shrugs*

[lookalikehuuh]

Originally Posted by jahsoul

I've read the opposite and saw that HJS were the only ones that didn't pop the CEL because of the Euro4+/TUV certificiation. I might be wrong though.. *shrugs*

I would double chek that information because if it were true that a 200 cell cat could be as effective as a 600-800 cell cat, wouldn't everyone be moving to that cat?

I say that becuase in theory it would be significantly cheaper to build a cat with 1/4 to 1/3 the amount of expesive exotic metals internally. Im sure auto mfgs would be down to save 60-75% on costs.