High Flow Cats

The cats on my 1997 Legacy 2.5GT are rusted and cracked, so I'm looking for places to purchase a Stromung High Flow Cat to replace them. I've seen them on Boxer4Racing, but that's it. I have placed a few orders from there before but the shipping is very expensive.

 

Anyways, anyone know where else I can find one? Any recommendations for other brands of HFCs?

 

thanks!

No one here has a high flow cat?

magnaflow, turboxs, spt

I wish I knew more about exhaust systems/had more $$ to get some stuff to make my own decisions. But I have seen and heard some good things about the spt ones.

I have a magnaflow HFC. Really only got it (other than legality of course) because of my 3" exhaust upgrade. I think it was around $95 or something on Jegs.

Thanks guys.

 

Bdubs, The Magnaflow has to be custom fabricated, correct? Is your car OBDII and does it need the oxygen sensors?

 

I can't seem to find any info on the SPT HFC, anyone have a link?

 

As far as direct fit for the 2nd gen Legacy and earlier Imprezas, I think my only options are RandomTech (around $600) and Stromung ($350). Both have the holes drilled for the oxygen sensors and are direct bolt on.

I knew I forgot to add something. You are correct, you'll need a HFC that has an o2 bung for the secondary sensor. On my 91, there is only one sensor, so that magnaflow works. I'm sure you can make it fit, but if you have found some with the bungs installed already, save yourself the trouble and get that.

 

Pretty much all the cats have to be custom fit and welded into the existing or new system. Any leaks in that area will more than certainly throw a code.

 

As for SPT High Flow cat, I think maybe they are thinking High Flow Intake? Because they certainly don't make an HFC.

you could use something like this :

 

http://cache.autoanything.com/images/products/schem/magnaflow/med/magnaflow_catalytic_converter_37871.jpg

thats made for a Gen 2 Legacy

Great Bdubs, thanks for the info. I may look into getting the Magnaflow fabricated at a local exhaust shop, probably save a bit of money going that route.

 

Also, did the exhaust get much louder or sound different with the HFC?

I actually already have UEL Borla-knockoff headers, so I wouldn't really want to spend the money on a new set of headers with a cat. Thanks though.

so getting a hi flow cat with a bung that fits the stock o2 wont set off the check engine light?

the stromung works great and is a nice piece. as far as where to get it, the only place i have seen it is http://www.boxer4racing.com. i plan on adding one to my 95 Legacy some day.....

going to a highflow single car will change the way your car sounds, we always add a resonator to the system to smooth it back out

Thanks.

 

I got a CEL just from the headers, and I had to use spark plug non-foulers to get rid of it. Anything that causes more flow to the second O2 sensor will throw a P0420 code, so I imagine that a HFC would as well. The only ways that I know to get rid of it are to use the spark plug non-foulers or get your ecu re-flashed to block the code.

 

I think I will go with the Stromung after all, with a custom mid-pipe and resonator. I don't think anyone around here welds stainless.

Resurrecting from dead...

I had headers and used a spark plug non-fouler to get rid of the P0420 code. My headers are now gone - rusted out. I put my old exhaust back on and don't have any codes. Is there a reason to remove the spark plug non-fouler from the 2nd sensor? What effects if any might it have on performance, mileage etc?

THANKS!

I am on my fourth pair of Magnaflow cats. The front and rear cats take turns failing within 2 or three months of each other. I start to hear a faint rattling sound at idle then I rev the car with my door open and hear the rattling even more while it decelerates. It has been a little over 2 months since I replaced the front one this time but not sure if its the front or rear now. What it is that keeps happening is the internals of the cats are failing and getting blown out through the tip as a powdery substance over time. I have an UEL header but I'm being told that is not the issue. My Subaru specialist is telling me that this is a common issue for these older 2.2 -2.5 EJ's when putting on after market cheap cats like Magnaflow or Eastern Catylitic. He told me that the only way to get this to stop is either buy a OEM exhaust off of a private person and saws all the cats off and put it on my car or buy an OEM because by law the salvage yards are not allowed to sell used cats for some reason. Either way I'm annoyed with this issue over dumb shit. I'm just glad that it is not screwing with the performance of the car. So I can put up with the rattle vs going to my exhaust dude and telling him I need another $130 replacement cat again. I would really like to either eliminate one of the two cats or gut one or both of them (I'm not a liberal so I don't care about the CO2). but that leaves me unsure of the CEL. I am familiar with the plug fowler trick but wondering if I gut the cats maybe I would need a fowler on both to stop a future CEL (my old friend P0420)? All I know is I had enough of chasing this issue for the last 2 years and would rather have no cats and no issues like my 05 LGT. The other issue is my 95 BK gets the sniffer up the tail pipe for emissions every year so I hate to do a delete and find out that I pulled my own pants down at the test and fail. Any ideas on this?

It could maybe be possible that you have some other issue running the car rich and the cats are getting burned to bits as they try to catalyze the fuel residue. You can try to see that by taking the temp of the cats with an IR temp gun and checking what your exhaust chemistry is like. There is info online how to do this, but I don't have a specific pointer. But, I'm pretty sure you would be getting bad gas mileage if this were the case.

 

It could be that the cats are made in a large Asian country the makes a lot of crap using virtual slave labor and sells it to us for so-called bargain prices.

 

If you didn't have cats you would need some kind of a cheater that makes the rear o2 sensor do something or other compared to the front o2 so that the ECU will think that the cats are doing their reaction job. I don't know for sure, but I think it goes inline in the wiring for the rear o2.

 

FYI, there is always lots of CO2 in exhaust. The cats are there to react out the CO, and the various hydrocarbon residue. If you were a liberal your only hope at reducing your carbon footprint would be to kill yourself*. Glad you have enough sense to not buy into their uninformed dogma.

 

* I'm not advocating this. I'm simply pointing out that modern people make a lot of CO2 no matter how hard they try not to and also that I've never met a so-called liberal who actually believes any of the things he says he believes, but rather believes that everyone else should do what he says while being exempt himself. It's really a rather morally and intellectually bankrupt dogma.

i have hollowed out cats on two of my subarus, one with a uel header and spacers on the rear sensors, one with stock exhaust and no spacers on the rear sensors and neither gives a code. the one with the uel gave a 420 after a while without the spacers tho, and the mileage dropped due to it.

My headers will be here soon. Don't know yet if I'll wrap them. But I have both cats replaced with new aftermarket direct fit units. I think it was about $450 for the cats. I hope I didn't waste that money on cats that will be dead in a couple months.

 

(after I replaced them I went to the local salvage yard and with a straight face asked them, "Do you buy dead cats?" It was fun.)

i have hollowed out cats on two of my subarus, one with a uel header and spacers on the rear sensors, one with stock exhaust and no spacers on the rear sensors and neither gives a code. the one with the uel gave a 420 after a while without the spacers tho, and the mileage dropped due to it.

 

I live in Pennsylvania and get an emissions test every year. They stick a sniffer rod up the tail pipe and give you a read out on a receipt that goes to our state capital. I really want to go catless but I'm being told that the front cat is the one that the O2 sensor gets its reading from for the ECU and the fuel injection to work properly. I'm driving with this thing grenaded internally as we speak. Would really like to hollow them out or gut them out but am afraid of the CEL becoming an annoying back and forth issue or not passing emissions. I could probably obtain an emissions sticker once a year if I really had to but would rather not have to deal with that shady situation either. Thanks for your reply

It could maybe be possible that you have some other issue running the car rich and the cats are getting burned to bits as they try to catalyze the fuel residue. You can try to see that by taking the temp of the cats with an IR temp gun and checking what your exhaust chemistry is like. There is info online how to do this, but I don't have a specific pointer. But, I'm pretty sure you would be getting bad gas mileage if this were the case.

 

It could be that the cats are made in a large Asian country the makes a lot of crap using virtual slave labor and sells it to us for so-called bargain prices.

 

If you didn't have cats you would need some kind of a cheater that makes the rear o2 sensor do something or other compared to the front o2 so that the ECU will think that the cats are doing their reaction job. I don't know for sure, but I think it goes inline in the wiring for the rear o2.

 

FYI, there is always lots of CO2 in exhaust. The cats are there to react out the CO, and the various hydrocarbon residue. If you were a liberal your only hope at reducing your carbon footprint would be to kill yourself*. Glad you have enough sense to not buy into their uninformed dogma.

 

* I'm not advocating this. I'm simply pointing out that modern people make a lot of CO2 no matter how hard they try not to and also that I've never met a so-called liberal who actually believes any of the things he says he believes, but rather believes that everyone else should do what he says while being exempt himself. It's really a rather morally and intellectually bankrupt dogma.

 

I'm being told from the Subie specialist that Magnaflow and Eastern Catalytic are cheaply made in some Asian country and are prone to fail. My fuel consumption is great. No issues there at all. I would like to remove them but the car wont operate properly without the O2 sensor or a gutted cat I'm being told. It sounds like I'm am being forced into buying a private sellers exhaust off another car and taking the original cats to get them installed on my current exhaust system unfortunately. I just find it hard to believe that nobody else has had this problem or has an alternative system that will work to be problem free with or without cats.

I checked, mine are Magnaflow.

 

The way I hear it the front O2 is for getting AFR correct. It is before either cat. The second O2, after the cats, is just for emissions to check that the cats did their job. It should detect the 'problem' of no cats or hollowed out cats and set check engine (there is a mod you can do to block this). And the up pipe probe at a state testing shop would detect the higher CO and HC levels if you do such testing.

ya, here the emissions test is only an obd2 plug in for 96 and newer, sniffer for anything older.

ya, here the emissions test is only an obd2 plug in for 96 and newer, sniffer for anything older.

 

The sniffer test is ridiculous in AZ. The dyno they use puts almost 3x the load on the vehicle in order to move it up to speed. I have seen engine blow while on the dyno.

Damn! I'm glad we don't have that here. I can't afford to buy a new car just to pass emissions...