Can you remove the catalytic converter and replace with a regular exhaust system?

Catch 22 on this, Your engine would not run right , gas mileage will go down, engine would run rich, and cause more problems, Check engine light would be on, it would throw a lot of trouble codes,plus it is illegal to do, no one will do this. But there are a lot cheaper after market catalytic converters to be put on, I would just check with an exhaust shop to see what they can find for it. Or you could find one on line and have an exhaust shop put it on for you.

As "Rowefast" suggested, take it to a local exhaust shop and have them install aftermarket converters. My guess is that there are other issues than just the converters.

After market cats are really not that expensive. If you live in Kalifornia be sure and use a cat that is approved for use in the land of fruits and nuts.

In order: NO, NO, MAYBE. Subies are notorious for NOT accepting aftermarket CATs; we've all been through this innumerable times, esp with the infamous PO420 code.

That right SubaruBoston, I remember now that you mention it. Memory is a fond thing to have.

Hi I have a 04 subaru forester xt 5 speed an I took my muffler off from my car an when I did it was fine but the next day I was going to work the engine light came on an the cruise control light was flashing idk by me taking the muffler off will cause that my car been fine and going into boost fine I just don't want to break my car and it has almost 200k. Please help.

Reducing back pressure screwed up the calibration of the )2 sensors so that the ECM is not happy. Try reading the code and clearing it. I suspect you'll see a CEL code for the front (Air/fuel sensor) O2 or the rear O2 (trim).

CLEAN Your CAT - Fix stubborn P0420 Here's what I did: On 2005 Forester XT with P0420, 1. Removed downpipe/catalytic converters. 2. Separated into upper Cat and lower Cat. 3. In a 5-gallon bucket, mixed 4 gallons water, 10 oz. Citric acid and 7 oz Oxalic acid. (Purchased on Amazon - $20) 4. Soaked main Cat in acid overnght, rinsed completely with water. 5. Soaked upper Cat about 8 hours, then rinsed completely with water. 6. Reinstalled Cats, ran engine until hot, then cleared P0420 and it never came back. DONE. P.S. For those of you that may be concerned about handling ACID, don't worry, just WEAR RUBBER GLOVES. The oxalic acid is what's in "Bar Keepers Friend" cleaning powder that you buy at the grocery store, and citric acid is commonly used in food to give it a "tangy" flavor.. Relax - it's not dangerous at all.

Ta dah! PLEASE keep us posted as your inventive procedure's efficacy ages. Thanks. Ern

(I cleaned my catalytic converters May 2019 at 208,000 mi, now have 222,000, all OK !)

Good for you Tom! My Ford F150 has 220,000 and I have never had to replace or clean a cat but I keep it running right.