If I remove both will it be loud and have any drone inside the cabin? Vehicle is a 2003 4Runner 2WD. Please any options much appreciated. I might just try and keep the secondary cats do some experimenting or possible add a resonator. My cats are clogged and wanted a quick cheap fix without getting new cats. But I also want a good sounding truck. Thanks


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BUMP


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Replacement magma flow cats can be purchased for around $50/cat and a local exhaust shoo shouldn’t charge more than an hour or so of labor total.

It’s better to replace the cats and not have to deal with O2 simulators and unnecessarily contributing to global warming.


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I have a V8 with secondary cats removed and a straight pipe. It sounds really good to me. But I have to admit. If you’re going to remove the main and secondary cats on a V6, it will sound like a ricer. It’ll have a lot of drone because my V8 does with just the secondary cats removed.
Depends what kind of sound you’re looking for, but it won’t sound deep and throaty.

Looking more of a throaty sound, non-ricer...maybe with all the cats removed and put a resonator or muffler before the stock muffler?


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it's gunna be hard to make it sound throaty no matter what you do...

Any suggestions? Reason being is that my main cats are clogged and ruining my o2 sensors.


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What makes you think your cats are clogged?? Are you throwing all kinds of codes?


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I agree with easy, on a V6 it’s hard to make it sound throaty no matter what. Your best bet is if you’re going to remove all of the cats, get a muffler like an 18in magnaflow and keep the resonator on at the tip of your exhaust. I’d stay away from Flowmaster since they tend to be kinda of tin can sounding

I keep going through o2 sensors and getting o2 codes...currently I have a code for bank 1 sensor 1...that sensor is only 6 months old


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If I only remove the main cats and leave the secondaries will it tend to clog the secondaries quicker?


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Not necessarily. A clogged cat is usually not too common unless there is another underlying issue that is causing it such as excess exhaust burn off or carbon being built up there. If you remove the main cats, you’re removing them from doing their job of keeping everything else cleaner behind them so you do take the risk of possibly causing more carbon build up on the secondary cats.

If you’re looking to remove all of them and not have to deal with possible clogging or anything, I’d say go for it. However, just keep in mind you’ll have to find an alternative to quiet down the exhaust if you’re not looking for a ricey type of sound whether it’s through a muffler or adding more resonators on it.

You’ll also have to live with the fact that your CEL will be on all the time since you’re removing the cats unless you get a bypass or tune to get rid of it.

Is there any oil inside of the O2 connectors, either on the engine or exhaust side of the connector? Are you using any kind of contact cleaner on the O2 sensor or connector?

Typically, if a cat is clogged it will not affect the upstream O2 sensor but a truly clogged cat will cause the vehicle to bog down at higher loads because the exhaust flow is restricted or blocked. If you still have normal power across the entire rpm band, I doubt the cats are clogged.

If your primary cats are clogged or you just decide to remove them anyway, I would remove the secondary cats as well because there are no sensors downstream of the secondary cats. To get it to sound "not ricey", you'll need to run a resonator in front of the muffler and stick to a OEM type muffler. A Flowmaster 70 or 60 series would probably work as well. It's probably going to sound like an uncorked 6 any direction you go. Let us know how it turns out.

My V6 is fully catless (URD equal-length headers and off-road Y-pipe) with the stock muffler. It didn't change the sound very much at all when I removed the cats, just added some rasp and is still pretty quiet. I started it up with just headers once while I was replacing the Y-pipe and it sounded amazing (way too loud obviously, but still, I could see potential). I'm sure if you remove the cats and add an aftermarket muffler and resonator you can make it sound alright

I've got a 07' Limited 4.0L with secondaries removed, no resonators just pipe and a 2 chamber flowmaster...had it turned down before the axle and it sounded almost identical to a V8, but the original setup I welded up was a glass pack and it was very raspy and ricey sounding , once I cut it out and welded the two chamber in it was a world of difference with the sound much deeper. I also have a custom 3" Mandrel bent intake system.