People tell me that removing my catalytic converter will greatly improve horsepower and gas mileage without affecting emissions too much.
Can the converter be gutted out? is there a free flow replacement?
Th

It will be better to leave thing as they are..... few dollard we save only polution more to our inveroment is not worth the trouble...

not to said don't pass smog... geting fine ....louder noise and for what ???


I use to do these thing in my early day..... but now I keep car as they are....

you can get a 3" downpipe with race cat, they are $$$ but might benefit some, although unless you have a highly modded engine and free flow cat back exhaust system changing or removing the cat may not be a great improvement in HP or MPG because of the resrtictive volvo muffler. it is best to do exhaust mods from the rear first and the cat last.

Dan

Possibly they didn't tell you your car will sound like a 20 year old pickup inside the cabin after you remove the CAT. If your cas has two O2 sensors then the computer will also throw a CHECK ENGINE malfunction.

Search this site for CAT, Catalytic Convertor, CAT bypass and you will turn up many tips.

KP

It's also illegal to alter/remove/bypass the converter; I believe there is a $10000.00 fine if the Feds or DMV discover that you have tampered with a pollution control device. I wouldn't recommend doing that. Just trying to expostulate.

Regards,
Bou Bou

I agree with these posts.

In my case I live in Thailand where the average bus puts out a smoke screen for a kilometer. My dealer (not a Volvo dealership) removed the cat and put in a bypass instead of spending money on a replacement under warranty. You guys don't know how lucky you are out there in civilisation !

Anyway - this is what I found. Helluva noise inside the car, similar to a trumpet player inside a large cave - for me, impossible to drive a car sounding like this. Might be OK for some immature teenager who likes advertising the fact though.

I had access to a friendly muffler dealer locally and played about with the exhaust systems he sold.

Adding almost ANY muffler (turbo style or straight through) at the rear of the car brings the noise almost down to stock, adding another small straight through muffler where the CAT used to be brings it back to stock levels. Adding the inevitable chrome piece of junk on the end (Thais love these - the bigger and shinier the better) does nothing at all, of course, except deplete your wallet. I practically had to fight them to take it off !

I left in the original Volvo pan muffler - I thought I would try to keep some back pressure on the engine/ turbo as the ECU is not modified and I don't want it to run rich. However, it did not appear to be particularly restrictive to us.

Power - after CAT removal bottom end power much the same, top end seems a little improved. However, I can't see any real difference after the addition of the mufflers.

FYI my car is only fitted with one O2 sensor which makes it a lot easier for me.

KP

I don't know where you live but in the US it is illegal to remove the catalytic convertor unless there was something wrong with the prior one. In California, the only way you will get an honest repair shop to put in a free flow catalytic convertor is if the one on malfunctions. Aside form the fact you can be fined heavily, the volvo, like others have noted, will put out errors in the codes because of the change. If you want to get more horsepower, there are other things to do, such as the free flowing exhaust and the chip mods. I highly recommend leaving the convertor alone. It's there for a reason.

Delgado
San Diego, CA