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Discussion Starter · #1 ·
New to forum, just bought my first tundra (owned several Tacoma's) was doing some routine maint and while changing my rear diff fluid and greasing the driveshaft I noticed 5 cats on my truck. Two inline for each header, then a big muffler then what looks like a small cat or resonator behind the muffler then the tail pipe. Just curious if I put another muffler on would a shop remove that last cat/resonator behind the muffler? It didn't have any O2 sensors on it.
 

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New to forum, just bought my first tundra (owned several Tacoma's) was doing some routine maint and while changing my rear diff fluid and greasing the driveshaft I noticed 5 cats on my truck. Two inline for each header, then a big muffler then what looks like a small cat or resonator behind the muffler then the tail pipe. Just curious if I put another muffler on would a shop remove that last cat/resonator behind the muffler? It didn't have any O2 sensors on it.
The cats are due to EPA.

The last resonator is just that, a resonator.

Depending on who's exhaust you go with, or if you do it yourself, they may or may not remove the resonator.

I did a custom exhaust on my 2010 RW, and left the resonator. On the new truck I just went with the TRD duals.
 
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New to forum, just bought my first tundra (owned several Tacoma's) was doing some routine maint and while changing my rear diff fluid and greasing the driveshaft I noticed 5 cats on my truck. Two inline for each header, then a big muffler then what looks like a small cat or resonator behind the muffler then the tail pipe. Just curious if I put another muffler on would a shop remove that last cat/resonator behind the muffler? It didn't have any O2 sensors on it.
Yep, four cats. I'd leave em alone and just get a good catback system. Wait, I meant I left mine alone and just got a good catback system (see sig).
 
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Discussion Starter · #6 ·
I'm not messing with them, I've just never seen a vehicle with inline cats before. I don't see how the motor breathes with all the crap in the exhaust.
 

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I'm not messing with them, I've just never seen a vehicle with inline cats before. I don't see how the motor breathes with all the crap in the exhaust.
Combined with the wacky stock multi chamber exhaust probably doesn't help either.

I figured I'd just replace the cat back with something reasonable. So far so good!
 
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Vehicles have had 4 cat's for a while. Like a long while. Like my Grandpa was still alive long while.

When was the last time you had a new vehicle if I may inquire?

I remember when I was younger than 18, a Ford Expedition had 4 cats. AND I am 36.

I was in Cali at the time, but still. That was 18 years ago.
 

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Well built catalytic converters do not really obstruct flow very much. The double walled reduced pipe in the system is FAR more of a problem then the cats will be.

With that said, aftermarket cats on a well built system will not be a restriction and pick up power. This varies from N/A to S/C trucks.
 

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I cut my two rear cats off.
How much did that change the sound of the exhaust ? I'm thinking of doing the same thing, already have the TRD catback on the truck, plan on getting 2 matching flanges then remove the secondary cats.
 
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How much did that change the sound of the exhaust ? I'm thinking of doing the same thing, already have the TRD catback on the truck, plan on getting 2 matching flanges then remove the secondary cats.
I removed my rear ones to send to install on my BAM race exhaust and it sounds very similar just a little louder but still manageable. I love my TRD exhaust but I am confident I will like the BAM much better. I was also told the rear cats are better than the front ones.
 
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