Removal of the rear cats...

MrBluGruv said:
MISINFORMATION PEOPLE!


Goodness, people have only been doing this for years, I would've thought it'd be understood now.


Your REAR catalytic converters have no efficiency monitors on them, so removing them makes no difference to the computer, it will never know the difference, you WILL NOT throw a code.


The exhaust chain in regards to emissions control flows like this:

Manifold -> 02 sensor (for A/F monitoring) -> primary catalyst (smaller set) on the down pipe -> 02sensor (for catalyst efficiency monitoring) -> secondary catalyst (larger set) -> rest of exhaust.


You should most definitely notice a volume increase unless you just have super quiet mufflers, in which case you may consider going that route first.
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Thank you sir for your input on this, so then i should be fine doing this...:D
 
Yeah, you're right. I was thinking about the fronts. I want to delete the front cats when I get headers so the rear O2 sensors must be turned off for that. Sorry. Brain fart.
 
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tbone said:
Yeah, you're right. I was thinking about the fronts. I want to delete the front cats so the rear O2 sensors must be turned off for that. Sorry. Brain fart.
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Yeh. Actually, with the easy availability of the Lidio tune (as well as others maybe, I had just gone with Lidio at the time), doing the full cat removal is actually remarkably simple on this car compared to some other vehicles.

It's a pain in the ass on my Camaro, I mean with the money I'd put into getting a special tune, which are typically considerably more than for the Marauder unless you mail in your entire PCM, just to run like a $200 off-road downpipe setup, one may as well just buy headers for $355 that bolt up to the factory cat-back and run that same tune.

I mean, it's nice for a mod like headers to be so cheap, but at the same time small mods are not cost effective at all really. :depress:
 
I deleted the rears for sound. I put Magnaflows on and it sounded stock. So off came the rear cats and on came the nice sound. That definitely made it worth it.
 
Your check engine light will come on, you won't pass inspection. And as mentioned, if they look for the cats you'll fail inspection until you put them back on.
Not a worthwhile "mod" in my opinion.
 
If you are talking to me, there is no visual inspection here.

My rear sensors are turned off, rear cat deleted, no light, and I passed the OBDII inspection with no problem. The front sensors are before the first cats, so how would the car know if the cats are gone? I'm golden.

If you're referring to airjordan, mrblugrv is correct.
 
tbone said:
I read up on it. Sounds like it's hit or miss down there on the visual.

The thing is, we have four cats. He can point to the fronts and say they are on the car. Plus no codes thrown. What can they say?

The sound increase really is worth it.

http://www.youtube.com/watch?v=6dBWYI6HHdA&list=LLBub0tbEpo6R8jPsLwF8TdQ&feature=mh_lolz
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Believe me it will be mostly a miss....

Not to many cars have 2 set of cats. When hey do the visual they will see a cat on each side.... they will have no clue that the Marauder is supposed to have 4 cats.

Not just the sound increase, you'll get a better breathing exhaust.
 
FrankJAG said:
Most inspection stations check for cats here in Texas.
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I guess that's one of the few perks of living here in San Antonio, never once had anyone look under the car. Or under the hood. Hell I once found a shop that asked for my plate #, VIN #, and mileage, and sold me the sticker right there. :eek:
 
airjordan2k8 said:
These people are saying that ill lose gas mileage and that it has 4.sensors
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You have 2 upstream and 2 downstream sensors. You can do without the rears by having them turned off by having a guy that is a tuner deactivating them via programming.
Just saying, allot of expense for not allot of benefit other than being noisier, I don't think you'll see allot (if any) increase in horsepower. Just my two cents LOL
 
If you are worried about the visual inspection you can always gut the cats. Horsepower wise it's not the best thing to do. The hollowed cats will create turbulence in the system and will not flow as well as a straight pipe. It will however give you more volume and not raise any suspicions come smog check time. A properly sized piece of staight pipe hammered inside the hollowed cat will provide the best of both worlds while providing a minimal restriction to exhaust flow.
 
Removing the rear cats will not cause any CEL code, period.

The rear cats sit right at the cross member where the transmission mount is so you say the trans was pulled and they couldn't unbolt the exhaust so they just cut the pipe to drop the transmission.

I had my rear cats deleted and went through 1 or 2 emissions testing here in Maryland, they did walk around with an angled mirror checking under the car and passed. Went through emissions last year with my whole new exhaust and only two magnaflow cats, they didn't say anything besides "sounds like a beast!".

When I removed my rear cats I noticed a better exhaust note and slightly better mid-high rpm range power, I also knocked a tenth off my 1/4, raced a Friday, removed the cats on Saturday and raced again on Sunday.
 
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ctrlraven said:
When I removed my rear cats I noticed a better exhaust note and slightly better mid-high rpm range power, I also knocked a tenth off my 1/4, raced a Friday, removed the cats on Saturday and raced again on Sunday.
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Perfect. THAT's what I'm talkin 'bout!

You know, come to think of it, this is actually one of my favorite mods.
It sounded way too wimpy before, even with the Magnaflows.
 
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Okay, I did this yesterday and added the 4" Tips.... remembered that I was gonna video the sound prior....

No error codes, much MUCH better sound. I can slightly hear a difference on the highway, seriously not noticable but idle and when you get on it, a much better sound.
 
Well explained ctrlraven... the guy said he will do it anyway but do keep in mind it will use more gas is this true?? Love that i can come here for all my questions..
 
airjordan2k8 said:
Well explained ctrlraven... the guy said he will do it anyway but do keep in mind it will use more gas is this true?? Love that i can come here for all my questions..
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Tell that guy to explain to you exactly how it could use more gas.


I swear, the things people come up with these days. Makes me wonder if 9/10ths of the auto hobby exists on urban legend alone...
 
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