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2014 Impreza WRX 5 speed manual
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Discussion Starter #1
Does anyone have any experience with a Magnaflow exhaust system on their Forester? My rear catalytic converter is vibrating on the bottom of the car and it can't be adjusted because it is badly rusted. Any input would be appreciated.

LIP89
 

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Discussion Starter #3
Thanks for the links. Primarily, I'm looking for anyone who knows about the compatibility of the parts found here 1998 Subaru Forester Magnaflow Catalytic Converter - 49 State Emissions. It's the rear cat that I'm looking at. Most of the reviews of the Magnaflow products said installation was easy and the parts fit. Then again, most of the vehicles from the reviews were American, so I'm just trying to cover my bases.

LIP89
 

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2007 Forester Sports XT 4EAT
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My mistake, I assumed you wanted a Magnaflow muffler, not a Magnaflow CAT. The quality of those on your link look pretty good, but are on the spendy side. :icon_eek:

A good muffler shop could weld on an an aftermarket CAT. I had a high flow CAT installed on my '03 X for under $200. :smile:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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Discussion Starter #5 (Edited)
Well, when you consider that I spent $413 to have a midpipe installed and $600 for front rotors, pads, and calipers along with an e-brake adjustment and rear brake cleaning... yeah, lets just say I don't know many cheap mechanics. That's why I'm trying to do this myself. I was told that the rear cat alone would cost $1,000 (yes, just the part). The front and rear cats from the above link together don't even break $500... and those are really good ones! Worst comes to worst, if I have trouble with the install, at least I'll know that I spent less on the part than the mechanic would have charged me for. I'd hate to pay for labor, though. That's why I'm looking for compatibility input.

@ Sleeper
You've obviously worked on your exhaust. Do you know the specifics on the hardware I would need? Assuming there are any, I would just reuse the ring seal between the two pipes. Is there any kind of sealant that gets sprayed around the connection? Do you happen to know what bolt size I would need and if I can get them in stainless steel? At a minimum, there are three (3) bolts/nuts. Two (2) connect the front and rear cats and one (1) is used to connect the brace on the rear cat to the transmission. I looked at an enlarged picture of the rear cat, and I noticed that there is a hole for a sensor. There are no sensors running to the rear cat currently on the car. Will this cause an issue? Thanks in advance for any help you can provide.

LIP89
 

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2007 Forester Sports XT 4EAT
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Nope, I researched, but since I don't weld... yet, I had my trusted muffler shop do the work. :wink:

You may need special wrenches (sockets) to remove the O2 sensors.

To loosen the exhaust hardware, spray with PB Blaster penetrating catalyst. Letting it soak overnight would be perfect. To get a better seal on exhaust gaskets, you can apply Permatex 81160, high-temp red RTV silicone gasket maker. An air impact wrench would be nice for any stuck exhaust harware. I'd also expect to break some of the heat rusted hardware. Not sure of the hardware size. I'd recommend using anti-seize on all the threads, including the O2 sensors, when you put things back together. :smile:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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Discussion Starter #7 (Edited)
Thanks for the tips, they should help a lot. At the moment, I'm just thinking about replacing the rear cat. Currently, when I crawl under the car, the only cat with sensors on it is the front one. Do you think the rear cat comes with some sort of plug if there is indeed an opening for a sensor?

LIP89
 

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2007 Forester Sports XT 4EAT
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AFAIK, you'll have two O2 sensors. The front one is used by the ECM when you're running "closed loop". It's also call the A/F, or Air Fuel sensor. The rear one is used to monitor the efficiency of the rear CAT... looks for excess O2, which means the CAT isn't functioning properly or something else up stream isn't right. That's where the P0420 CEL code comes from. The rear O2 sensor is usually after the rear CAT, but I recently discovered my '07 has 2 rear CATs & the rear O2 sensor is placed between the 2... meaning nothing monitors the rear most CAT? My '07 started it's life in California, so I suspect it has to do with the stricter emmisions requirements there. :smile:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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Discussion Starter #9
Silly Californians. On my car, both of the O2 sensors are on the front converter. I don't know if at some point there was one at the front and one at the rear, but that's where they are currently. Also, looking at the images from my link, there are 2 sensor ports on the front and 1 on the rear, but my car only has 2 sensors. Sorry if I seem obsessive about this, but I just want to make sure I get the right pieces and don't mess anything up.

LIP89
 

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Ah crap.. I'm back with my 05 XS
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If you saw LA in the 80s-90s, you would understand why we have strict emissions requirements :lol:
 

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AFAIK, you'll have two O2 sensors. The front one is used by the ECM when you're running "closed loop". It's also call the A/F, or Air Fuel sensor. The rear one is used to monitor the efficiency of the rear CAT... looks for excess O2, which means the CAT isn't functioning properly or something else up stream isn't right. That's where the P0420 CEL code comes from. The rear O2 sensor is usually after the rear CAT, but I recently discovered my '07 has 2 rear CATs & the rear O2 sensor is placed between the 2... meaning nothing monitors the rear most CAT? My '07 started it's life in California, so I suspect it has to do with the stricter emmisions requirements there. :smile:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
All XT's have 2 rear cats. Theres one in the downpipe, then one in the next pipe with the rear O2 sensor in the pipe right infront of that 2nd cat. The 04/05 also had one in the uppipe.


Lostinphilly, where in NJ are you located (I'm from the morris county area when I'm not up here for school)? There are a lot of VERY overpriced terrible dealerships in NJ for some reason, and not many would I trust to even change my oil. If they're not too far, I'd probably contact AZP installs as they're subaru enthusiasts who do mechanic work on the side.

For the exhaust, I'd look for a used headerback exhaust from any 2.5 nonturbo impreza/forester, or get a local welder/exhaust shop to weld up a custom system with some cheap magnaflow universal cats.
 

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All XT's have 2 rear cats. Theres one in the downpipe, then one in the next pipe with the rear O2 sensor in the pipe right infront of that 2nd cat. The 04/05 also had one in the uppipe.
The '07 is my first XT. :wink: You have to admit it's odd to monitor the first CAT with the rear O2 sensor, but not the second CAT? :confused:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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Does anyone have any experience with a Magnaflow exhaust system on their Forester? My rear catalytic converter is vibrating on the bottom of the car and it can't be adjusted because it is badly rusted. Any input would be appreciated.

LIP89
I have experienced to use magnaflow and it sounds so good. I think you have a wrong use of the rear catalytic converters that leads to bad rust.
 

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Discussion Starter #16
I contacted Magnaflow about the rear catalytic converter, and they said that, based on the vehicle they tested, there was one sensor on the rear cat. Their image of the front cat shows two O2 sensor slots. Here's the problem; I only have two O2 sensors. Although the original exhaust was replaced several years ago, I highly doubt that an O2 sensor could have been removed without some kind of negative consequence. My new question now is does anyone know what the stock exhaust layout is for a 1998 Forester? Does anyone else make a really good catalytic converter that I could use instead? Magnaflow's products suggest there should be three O2 sensors while the car only has two. I'm starting to think that maybe I should just deal with the rear cat vibrating on the underside of the car when I downshift. :crazy:
 

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Not saying you should buy this one, but read where it talks about the O2 holes. It comes with 3 and a plug for one of them. It sounds like the previous person to change you exhaust just put one of the O2 sensors in the wrong place. I believe the 4 wire sensor goes in the rear and the 3 wire sensor goes in the front. Plug the 3rd hole!

Subaru Forester 2.5L dual catalytic converter ** NEW **: eBay Motors (item 200426539523 end time Jun-08-10 19:03:22 PDT)

Edit:
I'm a cheapskate and have a welder, so I would probably buy this one and make it work. Replace both cats if you can. It will pay off in the long run.
 

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Discussion Starter #18
Thanks for the link. The problem is, that's a cat for a 2002 Forester or later. On my 1998, the front and rear cat are quite distinctly two different pieces. Also, I was hoping to upgrade if I decide to go through with this. If I can find a plug, all I really need to do is find where the two O2 sensors are supposed to go. I wonder if the mechanic that did the work would remember the original layout.
 

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Discussion Starter #19
Well, it's been a year but I'm back to working on my 1998 Forester's exhaust. I stopped by the dealer to price out the parts and nearly had a heart attack. They wanted $980.00 for the front catalytic converter and $542.00 for the rear. Therefore I took a second look at the Magnaflows that I had my eye on. Via Amazon.com, they cost $240.00 and $158.00 respectively. It boggles my mind that the performance components cost less than the stock parts. Anyway, if I do end up adding this project to my list, I'll definitely go with the Magnaflows. For anyone who cares, the two converters can be found here....
Front Converter

and here....
Rear Converter


John / LIP89
 

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I have bought Magnaflow parts on eBay before at good prices. Shipped in the US would be even cheaper!
 
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