Thread: Exhaust significantly quieter with cat?

I wanted to know how much quieter a car is with the catalytic converter vs without it. If anyone has removed/reinstalled theirs can you tell me your experience. Thanks

NA or Turbo?

It wasn't all that much louder when mine went off. Though the exhaust tone did change.

Sorry, turbo. I have a magnaflow muffler and magnaflow resonator but it still annoys me with the droning sound. I dont mind if it makes noise when im getting on the throttle but normal acceleration and idle shouldt be loud in my opinion.

The cat is removed, it was like that when i bought it so I dont know how loud it was with it in there. I intend to replace the cat at some point and am wondering if it will help solve my noise problem.

IDK how it is without the cat, but I know mine's still droney as all hell with a cat. Exhaust fitment under the car has EVERYTHING to do with it. I managed to keep the exhaust from touching any part of the chassis/body for all of one day, and the quietness in the cabin was UNREAL. I'm planning on sorting this out in the spring. I'm thinking that some eDead or something of that nature with a foil covering (to keep the heat at bay from baking the material) will suffice for a damper between the exhaust and body of the car.

I’ve had de, ve all with and without cats, the de and ve were very loud and droney for a dd car with no cat. I put at cat and resonator in and they quite down a lot. They still had a bit of a drone but it was manageable with a turn of the radio.

Right now I have a vet with a 3inch turbo back, with magnaflow high flow 3inch cat, and vibrant exhaust 3inch straight through, and the vet has been the quietest by far. I would recommend a cat if Ur a dd driver.

If I can find the pdf I had on a dyno run with cat, no cat, and test pipe and there was an hp gain of 1hp on avg. So I would take the quiet and no ticket, In Ontario Canada u can get a 400fine I think for no cat and Ur car towed.

What size piping? My exhaust is 2" id with no cat and it is pretty much silent at idle. I've ridden in stock cars that are louder than mine. When I open up my 3" cutout at the downpipe, its a different story. Best of both worlds. My car is turbo by the way.

Its the magnaflow muffler that's causing the drone, my car when I got it was loud and raspy (2.5" vrs exhaust with magnaflow muffler) I daily drive my car 56 miles one way to work, it got really annoying and I installed the longest resonator that would fit with the cat on, that got rid of the rasp but the drone is still there
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since my engine just went in my car I'm going to refigure everything, and I plan on changing the muffler, someone I know had a magnaflow muffler on their se-r and changed it out to a sti muffler, no more rasp and no drone, a world of difference
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Try changing the muffler first it should be cheaper than buying a new cat.
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on my ga16 the cat rusted out so I took it off and it wasn't any louder but the tone did change
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But your results may vary because I'm talking about non turbo cars.

I think the drone will always be there no matter what you change.

Get an STI muffler and call it a day. I never hear my exhaust, even when getting on it. People on the outside say differently.

Please ignore the A/F rod rattling
YouTube - Sentra Dyno Run from the Back

I have 2.5" mandrel bent JGY piping. Id have to get under the car to find out what model resonator and muffler I have, I can tell they are magnaflow by looking at them but wont be able to take measurements until the ground dries out a little bit.

I always heard that turbo cars were a lot quieter so I am surprised this car is so annoying. Maybe im just old now... LOL

Vadim, where do you get these STI mufflers? Unfortunately STI is only a 3 letter word so the search function is not that helpful. You video gives me an error by the way.