Im am at a complete lose...i need to replace my catalytic converter(PO421) and noticed that Monty has 3 cats(y-pipe has 2 abd another one behind it) and i was wondeing if there was a need for the one behind the y pipe, also is there a need for the two mufflers (resonator)? It seems like all of this is restricting the air flow. I have searched the google world for over a week and was not able to find any information on it. The local shope here have informed me that it is an overkill but wanted to if someone here had removed the cat and resonator? Thabms in advance and apologize if this has been covered before
Cat back question....
- Thread starter pmatos
- Start date
Painted Mountain
New member
No easy answer outside of it is required to keep computer happy. Your state will most certainly require it. Some countries down under let the air flow freely using o2 censor tricksters.
Inyo_man
Don't piss down my back and tell me it's raining.
P0421 can also tell you that the O2 sensor on either side of the upper cat is faulty.
I'd suggest testing the O2 sensors for resistance before replacing the cat(s), it's much cheaper.
In regards to the muffler and resonator...
I replaced the suitcase size muffler with a much smaller unit and deleted the resonator years ago.
The old muffler was very dinged up from contact with rocks, so the smaller unit doesn't hang up on obstacles as much.
Deleting the resonator does increase the exhaust note, but it's not bad in my opinion.
Cheers
I'd suggest testing the O2 sensors for resistance before replacing the cat(s), it's much cheaper.
In regards to the muffler and resonator...
I replaced the suitcase size muffler with a much smaller unit and deleted the resonator years ago.
The old muffler was very dinged up from contact with rocks, so the smaller unit doesn't hang up on obstacles as much.
Deleting the resonator does increase the exhaust note, but it's not bad in my opinion.
Cheers
My sensors are prerry much rusted/welded in place so i figured i would just replace the y-pipe cat instead of trying to pull them out to test them
Inyo_man
Don't piss down my back and tell me it's raining.
If you're asking about the muffler I installed, it is an Aero AT2525XL.
Can you increase the pipe to three inch and still pass smog in NC?
Some fellas over seas claim it has increased performance.
Im going to the muffle shop tomm to see if i can increase the pipe abd to see what the overall damage to my pocjet will be. Endes up with the rockauto y-pipe it dropped in price and figured it woukd be a good time to snatch it since they inky had 3 left
cr4x4cruiser
Observer
Catalytic converter removal offers negligible "performance" increases, in today's vehicles - especially those that have OBD-II [+ above] standards...
Truth be told, unless the CC was/is clogged [which will definitely stifle performance] removing such is merely a placebo [meaning, you convince yourself it runs better... faster... jumps higher... etc.
More likely, removing such will create more negative aspects... go ahead, mess with that vehicle's brain.
Increased performance? We're talking about a truck that is well over 2 tons & aerodynamic as a large garden shed ... what exactly is the need [or, want]?
For the monies required to extract "more performance" out of any given Montero you would likely find the cost far exceeds the value of it.
To each their own... but keeping it stock is keeping it simple.
- Wm.
Truth be told, unless the CC was/is clogged [which will definitely stifle performance] removing such is merely a placebo [meaning, you convince yourself it runs better... faster... jumps higher... etc.
More likely, removing such will create more negative aspects... go ahead, mess with that vehicle's brain.
Increased performance? We're talking about a truck that is well over 2 tons & aerodynamic as a large garden shed ... what exactly is the need [or, want]?
For the monies required to extract "more performance" out of any given Montero you would likely find the cost far exceeds the value of it.
To each their own... but keeping it stock is keeping it simple.
- Wm.
JohnnyBfromPeoria
I'm Getting Around To It
I'd keep it stock, but a cat-back system with stock diameter pipes would get you a less-restrictive (i.e., louder in most cases) muffler. I personally wouldn't change pipe diameter because of the engineered scavenging effect the original equipment provides. I happen to think my 95's muffler is too quiet, so if I were to change anything, I might look at a DynaFlow VT muffler that has a spring-loaded flap in it so it stays quiet on the road (drone drives me nuts) but opens for less restriction under higher load conditions.
John B.
John B.
'round n' back again
Explorer
exhaust design is tricky ; like camshafts. change one thing in the exhaust and it will give you unwanted changes in another place in the rpm range.
Almost always you want to step the exhaust up toward the tail pipe , but not too quickly. big tail pipe fine, too big up front and you will have every sort of trouble getting your engine to run properly.
with japanese cars, it has been my experience that the only "changable" is the muffler. Even then on the mitsu its not likely you will gain much all around improvement.
in my view a very well maintained factory system is the odds on favorite for daily driving.
saying that , a big tail pipe will make a lot of noise without compromising the rest of the system.
Almost always you want to step the exhaust up toward the tail pipe , but not too quickly. big tail pipe fine, too big up front and you will have every sort of trouble getting your engine to run properly.
with japanese cars, it has been my experience that the only "changable" is the muffler. Even then on the mitsu its not likely you will gain much all around improvement.
in my view a very well maintained factory system is the odds on favorite for daily driving.
saying that , a big tail pipe will make a lot of noise without compromising the rest of the system.
JohnnyBfromPeoria
I'm Getting Around To It
Good synopsis, R&B. Let's hope people listen.
John B.
John B.
Toasty
Looking for that thing i just had in my hand...
My exhaust is trashed, I'm going to change some things in order to R&D more power. We'll see how it goes but the plan is for higher volume of cooler air in and better flow out plus a dyno tune. As much as i want to try the 3.8 swap i can't justify it since my engine only has 60k miles.