The O2 sensors in your car are tuned to the cats currently in the vehicle. If you replace the cats , the ECU and O2 sensors will think something is wrong with the cats and start throwing codes and it quickly becomes a nightmare- this is ESPECIALLY true with the cheap cats because the cats are emissions system which is high-priority in the ECU (and legally in the USA) so once it starts throwing codes the ECU starts turning things off and hindering performance... basically a potential money pit. So if it ain't broke don't fix it.jpv74 wrote: ↑Thu Aug 04, 2022 7:27 pm Hey Gauc.....I am a newbie with a Subie as well. My car has a JDM 2.0 installed by the previous owner but it is not dialed in yet. The car boggs down in second gear and jumps to overdrive when climbing hills. I took it to a Subie shop and they are telling me they think the cats might be clogged but cant say definitively. They ran it with no exhaust and felt it was peppier with more air flow. We decided I would order a cheap cat section of pipe off of Ebay and just try to see if the performance improves with a new but cheap aftermarket double cat section of pipe. I personally dont think it will resolve my issues but willing to throw a couple of hundred in the pot to give it a chance. So now my question.......you say Dont replace those cats!!!! Educate me please.....mine have 183k on them.....might be partially clogged.....keep em or replace em? thanks
So, should you keep them?
You only have one post and just listed that you have a 2.0L. Since this is Baja forum I would assume it's in a Baja but can't always be sure. Also I don't know if it's an NA or Turbo. If it's a turbo, then I'm totally out of my league because I have basically no hands-on experience with those. If it's an NA, it's a 2.0L hauling a 3,500lb car- the performance is going to suffer regardless. Bajas were made for a 2.5L NA in the Legacies and Foresters, not the little motor for the city cars.
Also for what it's worth my stock 2.5L NA with now 240k miles has struggled going uphill from the day I bought it 90,000mi ago. Especially bad when driving through somewhere like WV. Fine for a day trip but would not do it on the regular, and especially not with a load.