So my cat started rattling at the 1600 RPM mark recently so I brought it to a muffler shop. They said it was the honeycomb that loosened up inside the cat, and to prevent the rattle they would have to install a new one which would be $400 for the cat and labor. So my question to whoever could help me out is are there any other alternative options? The people at the muffler shop told me removing the honeycomb would actually make the car run worse due to no back pressure. Is that true? And if so, is my only option to get a new cat installed? The cat they would be installing is an AP cat. Has anybody heard anything about AP cat's reliability and whether they put out the same power? Any info is appreciated. Thanks so much.

 

correct me if im wrong..

but busting out the honeycomb will basically make it like a test pipe...i know some people do this to their stock cats just to avoid spending extra money on an actual test pipe...depends on budget, state laws on exhaust, what you expect out the car, and what you want the car to sound like...

i am in the same boat my cat needs to be replaced but i dont drive it hardly and i am about to sell it and going to suggest replacing with stock cat, test pipe, or just busting out honeycomb to him/her...

 

I'd either get an aftermarket high flow cat and install myself, or get an OEM one (spendy), and install myself. High flow cats have dyno'd more than test pipes. Search around for the dyno info. How much of that $400 is labor? It's an easy install. Also, JDM ITR cats won't work on USDM caRs.

 

Do you have emissions in your state? If you don't I would find a used cat, or just get rid of that honeycomb. Catalytic converters are not cheap, I have seen some new OEM cats cost near $1000 dollars. You are lucky your car only has one.

I have ran many test pipes in the past, and never seen any problems aside from 02 codes.

 

Honeycomb loosening up inside the catalytic converter can be indicative of too much fuel pressure and running too rich. Been there done that. Tyrant - Carsound is a high flow cat. Lack of back pressure absolutely will kill power and the gains made from exhaust mods on an ITR sometimes can be a trade off of low end torque for high end horsepower depending on what other mods you have i.e. intake, header etc the results can either be beneficial or in some cases detrimental. I've personally ran the Carsound high flow cat myself and found it drones a lot. I wouldn't want to do a long road trip in it. Take 4 Advils and call Midas in the morning.

 

Dave S. sells hi-flow cats. You tell him what you have for a header and 'B' pipe and he custom welds a cat for you. He provides excellent workmanship.

smsptech@***.net

He sold me an obdII 2 1/2" in and 2 1/2" out, for my ITR JDM 4-1 header with a stock USDM 'B' pipe. It was 17" long and had one bung hole.

He sold me an obdII 2" in and 2 1/4" out, for my DC 6504 AHC 4-2-1 header with stock USDM 'B' pipe. It was 17 5/8" long with one bung hole.

 

I bought my cat from Dave a few years ago and am quite happy with it.

 

Removing the cat or gutting it might cost you a little low end torque but the back pressure issue is a myth. Sounds like the muffler shop want to sell you a cat and 400 bucks seems a bit high to me. Read Mike Khojima's book on Honda engine building, he explains the back pressure issue well.

 

THanks for all the replies people. Right now I'm deciding between just removing the honeycomb inside or ordering a cat and having a friend install it. I'm just afraid the same thing is going to happen again. Or does it only happen w/carsound cats?

 

Removing the honeycomb could foul your 02. I wouldn't advise that. Like I said before though, the fact that this failed MAY indicate that you're running too rich or that you have an ignition problem. Unburnt fuel traveling through the exhaust can be the original cause. You should get a good read on your plugs to diagnose whether this is the case or not. You may also want to check for codes. It could just be wear and tear but it only takes a minute to look for possible symptoms.

1. Has your car been misfiring or idling off especially in cold?
2. Any EXCESSIVE or fresh black stains on your bumper near the muffler?
3. Any unburnt fuel smell?
4. Any smoke other than the small puff that is typical of our cars when engaging vtec or changing gears?
5. Any unburnt fuel on plugs?
6. Any cel codes?
7. Do you have an aftermarket fuel pump, regulator, or ignition?
8. Are you running the correct temperature plug?
9. When is the last time you changed fuel filter?

 

$400 is incredibly high! I had a cat installed in the past 3 months after I bought my ITR with a straight pipe.
These are the following car-sound cats for CA:

Part number 46034
MSRP: $566.84
INLET: 2in.
OUTLET: 2in.
CONFIGURATION: Center/Center
BODY SHAPE: Round
BODY LENGTH: 11in.
WIDTH: 5.125in.
OVERALL LENGTH: 15in.

PART#: 41405
INLET: 2.25in.
OUTLET: 2.25in.
CONFIGURATION: Center/Center
BODY SHAPE: Oval
BODY LENGTH: 12in.
WIDTH: 6.5in.
OVERALL LENGTH: 16in.
FEATURES: Universal Converter-Application Specific

The 2nd one is 2.25in piping. I believe I did that one, I can only remember once I get home. I had it installed all together for about $250. So $400 is too expensive. Also these are Cats for good ol CA. We have more restrictions here....

 

I'm in the same boat looking for options as the cat converter started rattling too on my car. If I cant find anything locally I think I'm gonna go with Dave@smsp's option. I hate the angry bee sound of test pipes.

 

wow where are you guys shopping? I bought and had installed a magnaflow highflow cat at darryls mufflers for under 200. granted they had to re use my stock flanges, but i was running a test pipe any ways so they just cut a chunk out of the test ppe, stuck the cat in there n welded it up.

 

so... this is what i do.
i had a carsound cat as well. and it failed the E test on me. and it was rattling.
so i gutted out the cat. now it looks like a cat. so it WILL pass the eye inspection if that ever happens.

i swap back the oem cat and the header just to pass the e test and put the "gutted" cat back on for 2 years. and repeat. :D

 

Some people are saying that the gutted cat is worse than it is good. Any truth to this or is it going to be pretty much the same thing with and without the honeycomb?

 

It would be like a test pipe if you can figure out a way to get around the 02 issue but with the 02 mounted you can get codes 61, 63, 65, 67. If your mixture is too rich which should always be suspected when a catalytic converter fails - you can get codes 45 and 71, 72, 73, 74 which can effect your performance. This is why I'm suggesting that before you make a decision you check into the cause of the cat failing. It could be wear and tear but sometimes when the honeycomb fails like that it can be because of unburnt fuel going through the exhaust, build up of phosphorus or other contaminants etc.

With a blocked catalytic converter the exhaust gasses cannot properly escape so they travel back to the engine which can cause it to stumble etc. Removing the honeycomb from the catalytic converter would remove the blockage and therefore allow the exhaust to flow again but 95% of the time when a catalytic converter fails there is an underlying cause. Ignoring the cause by attempting to solve the symptom is not recommended. You should check your cap, rotor, plug wires, plugs, and if you have an aftermarket fuel pump or aftermarket regulator those would be suspect also.
You may also want to consider changing your fuel filter while you're getting a tune up.

For those that have hollowed out their catalytic converter.. How do you get around receiving 02 codes? Are you remounting the 02 somewhere else?

 

http://www.inlinefour.com/blcelelad.html

A cheap way to avoid most o2 codes, and fouling your sensor. Hope this helps man.

 

thanks for the link LankorDie

 

Great tip! Wish I knew about this back in 2001 when I was having all sorts of probs.

 

Just buy any old integra cat from 98+ from a gsr ls or rs they all work the same no difference. Way to know if its good or not hold it up to a light and if you can see the light its good if not its bad. They cost less then 200 used and installing them your self take only about 30 mins. Not hard at all.

 

Thanks man.

Its a great option for people who are still running unmodified ECUs.

 

i think you might end up busting up another new "cat'. i managed to bust a SMSP cat, had the honeycomb rattle. fix the problem soon because eventually you might get stranded. the exhaust system gets clogged.