alytic converter with a hacksaw and replacing it with some hose clamps and that flexible exhaust hose shite they have at auto zone

it's on a '94 Mazda Miata, which I'm pretty sure needs to meet only a safety inspection being pre OBD-II, confirm or deny this suspicion pls

12/11/2008 4:48:08 AM

yes, safety and visual only. your only concern is if the inspector looks under the vehicle, sees it missing, and decides to make a deal about it.

12/11/2008 5:28:39 AM

its a federal crime. could get a big fine

better idea would be to just hollow it out so you cant tell by looking at it

12/11/2008 7:12:51 AM

HOLLOW THAT BITCH OUT

12/11/2008 7:43:44 AM

can anyone provide some more info about the specifics of the relevant laws, amount of the fine, examples of people getting ticketed (how / why they get "busted"), etc?

I hear about people eliminating the cat in various ways all the time, I've never heard of anyone getting a fine for it... could I just claim it rusted out and I was repairing an exhaust leak?

12/11/2008 8:06:17 AM

No. If they notice it is missing then they are going to say you should have replaced it with a new cat if it were rusted out. You can get high flow cats from Summit Racing for $150 so there isn't much of an excuse if you get busted. It's pretty damn easy for them to look at your exhaust and see if there is a catalytic converter somewhere along the pipes.

I doubt you'll get a fine for it. You just won't pass inspection. With the new inspection laws you won't be able to renew your plates so it's a double loss.

On the plus side, your car is really low and probably difficult for them to thoroughly inspect for exhaust. If I were an inspector and some buzzy Jap car came in a missing cat would probably be one of the things I'd be on the lookout for though.

[Edited on December 11, 2008 at 8:32 AM. Reason : l]

12/11/2008 8:29:26 AM

so I did some reading and it looks like there are two facets to this

first removal of or tampering with an emissions control device is like a $2500 fine but virtually impossible to prove

second any manufacturer-installed catalytic converter must be present to pass even the visual inspection

so I think I'm going to do as recommended and hollow it out... then sell the innards for scrap, as apparently the scrap value is anywhere from $20 to $100 depending on the cat

while I'm thinking about this, what's a good way to actually hollow it out? it looks like I'd have to cut it open and reweld it if I wanted to collect the innards for scap, which isn't really an option on the budget I've set for this ($0 or less), so I'm wondering if there's any other approach than a broomstick

[Edited on December 11, 2008 at 9:18 AM. Reason : .]

12/11/2008 8:53:59 AM

big drill.

12/11/2008 9:34:54 AM

pry bar and hammer

5 mins of your time

"test pipe" is born

12/11/2008 9:41:54 AM

Cut it out, take something like an old tie-rod, pry bar, or the likes and break all the crap out, then re-weld it back in.

I have a gutted 2.5'' cat I can sell you if you are interested.

[Edited on December 11, 2008 at 12:45 PM. Reason : .]

12/11/2008 12:45:20 PM

unbolt it.....

12/11/2008 12:51:38 PM

Quote :

"On the plus side, your car is really low and probably difficult for them to thoroughly inspect for exhaust. If I were an inspector and some buzzy Jap car came in a missing cat would probably be one of the things I'd be on the lookout for though."

Removing the cat alone isn't enough to increase the exhaust tone to the point that the inspector would be suspicious. Tiberius, does your catalytic convertor not just unbolt at both ends? (you mention a hacksaw). In the past I used to unbolt my cat and put in a test pipe for the GS-R. And once a year, when it was inspection time I'd just bolt the cat back on for a few hours of the day.

12/11/2008 1:26:50 PM

I assumed he had an otherwise modified exhaust if he was talking about removing the cat.

12/11/2008 1:34:50 PM

Quote :

"In the past I used to unbolt my cat and put in a test pipe for the GS-R. And once a year, when it was inspection time I'd just bolt the cat back on for a few hours of the day."

Quote :

"3 WHP INCREASE"

12/11/2008 1:41:57 PM

^^Thats even more of a reason for nobody to notice a sound difference, given the muffling capability of the stock muffler.

^haha, doubtful. Also, I stopped doing it after one year. Didn't help that there was a slight leak where the test pipe met the exhaust. In between high rpm gear changes it'd whistle like a BOV, haha.

12/11/2008 1:57:13 PM

if you have an obdII car and don't want to pay for a simulator, you can always install a spark plug defouler. you might have to drill it out to fit the sensor, but it works like magic.

http://www.honda-tech.com/showthread.php?t=1841240

worked on my buddy's rsx when the cat went

[Edited on December 11, 2008 at 2:06 PM. Reason : ]

12/11/2008 2:04:57 PM

1" pipe, hammer, dust mask to keep carbon out your lungs, little effort. done.

12/11/2008 2:39:53 PM

^^ it is a 94...

12/11/2008 4:40:15 PM

^^THANKS FOR THE CALLS SATURDAY HOMO

[Edited on December 11, 2008 at 6:31 PM. Reason : where's my tekonsha damn it ]

12/11/2008 6:30:22 PM

unbolt it and knock the catalyst out, its a honeycomb similar to ceramic, very easy to do

12/11/2008 6:46:09 PM

what happens on an obdII car

12/11/2008 7:07:55 PM

it'll throw a code and not pass inspection



best solution, unless your's is plugged, leave it alone, gutting will cause stagnation and recirculation, its basically like a diffuser and nozzle with that much volume that cancels out your scavenging, especially as close as your's is to the head

12/11/2008 7:13:04 PM

why do you want to get rid of the cat?

12/11/2008 7:22:04 PM

^yeah i forgot to ask that too.

12/11/2008 8:36:16 PM

MOAR POWR

12/11/2008 8:36:51 PM

Have you considered a full race exhaust system from Racing Beat? they have one with a presilencer instead of a cat, full stainless, and doesn't sound bad. It has a stock look to it so it won't attract attention. Of course it's not going to be cheap, but they really make some of the best Mazda exhaust systems around... my 3" racing beat exhaust on my Rx-7 turbo is very quiet for 3 inch.

http://www.racingbeat.com/FRmiata.htm , get the power pulse muffler and race connecting pipe

[Edited on December 11, 2008 at 9:06 PM. Reason : link]

12/11/2008 9:04:55 PM

doesnt megan racing al make decent stuff for that car as well?

12/11/2008 9:29:38 PM

Quote :

"the budget I've set for this ($0 or less), "

12/12/2008 8:10:11 AM

cat vs. test pipe is most seriously a 4whp increase on back to back dyno runs on a B18 2nd gen integra...

flex pipe would probably kill that potential increase, and it's a shitty rig for a cat-replacement.

If it makes you feel any better, my car was inspected with a test-pipe (back in the day) and nobody knew the difference... it even looked like a glass-pack mufflah


spare the saw, get another car

12/12/2008 8:54:48 AM

Quote :

"Tiberius, does your catalytic convertor not just unbolt at both ends? (you mention a hacksaw)."

due to practical concerns (namely the car being lower than a snake's belly) I hadn't actually looked and assumed the worst case scenario... however, upon further investigation, it is in fact bolted on. I am borrowing some jackstands today to get this bitch off.

Quote :

"why do you want to get rid of the cat?"

thread has pretty much nailed that one on the head, I have too much time on my hands right now and I want my 3-5hp back

12/12/2008 9:07:04 AM

^be prepared to deal with stuck bolts. Just think of all the heat cycling those bolts have gone through and the road grime they've been exposed to. I'm not saying you wont' be able to get them off, but get ready for it to be a huge bitch.

Quote :

"cat vs. test pipe is most seriously a 4whp increase on back to back dyno runs on a B18 2nd gen integra..."

You serious Clark? What about a B17A with much higher flow?

12/12/2008 10:57:08 AM

It's in a book i bought about 4yrs ago... let me link the book

http://www.amazon.com/How-Build-Honda-Horsepower-Dyno-Verified/dp/1884089607


there's all kinds of dyno runs, D15B7 up to B20 (might even be some NSX shit in there).... of course most of it revolves around the B16's and B18's

12/12/2008 11:15:43 AM

I used to run around in my trans am with a 3" off road pipe and a cutout and it was cool for a while but then it really becomes a pain in the ass when the O2 sensors go bad quicker and when I would try to get it inspected I would have to find a place that was "friendly".

A few years ago I would tell you to gut it or take it off in a heartbeat but now I realize it can just be more of a pain than it is worth.

12/12/2008 11:19:51 AM

Quote :

"MARGINAL POWER GAINS"

Quote :

"OBNOXIOUS EXHAUST RESONANCE"

12/12/2008 11:29:13 AM

^I didn't have annoying resonance. My aftermarket exhaust does have a resonator though.

Hmm, seeing as how the GSR is coming out of regular duty I wonder if I should slap the test pipe back on. My car's so low to the ground that I doubt they could tell at an inspection shop. Then again, whats the point really (not like i'm going to race it). Better gas mileage?

[Edited on December 12, 2008 at 11:34 AM. Reason : k]

12/12/2008 11:33:14 AM

I doubt it. I'd say you'd only see the gains if you frequently operated the car around 4k and up rpms.... other than that maybe the better exhaust note


--I've a D15 civic with header, full 2.25" exhaust with resonator and STOCK REPLACEMENT muffler, and swapping a test pipe for my catalytic converter more or less doubles the volume of my already terrible exhaust tone.


on another note, i fabbed a spring-loaded cutout around september 2007, ran it for about a month before I removed it and made a flanged cover plate for the opening. other than the continual rattling of the flapper (obviously), it would be fairly mild until i got that bitch of a motor wound tight

12/12/2008 11:42:21 AM

^I do spend a lot of time above 4,000rpm accelerating around town. Also, anything about 70mph necessitates that I be above 4,000rpms, lol.

I have a full exhaust, so I don't really remember any louder tones with the test pipe (though I'm sure it was sligtly louder. Actually I think it was annoyingly loud at partial throttle.

12/12/2008 12:12:44 PM

once you're fed up with the IACV enough,you'll idle at 4000

12/12/2008 1:33:11 PM

I'll go ahead and say it.
That's a pretty fucked up thing to do for such a minimal gain on a street car. It's on par with littering because you're too lazy to carry your trash in the house and put it in the trashcan.

12/12/2008 2:11:25 PM

^you don't know how clean his exhaust is.

12/12/2008 2:20:15 PM

Quote :

"^be prepared to deal with stuck bolts. Just think of all the heat cycling those bolts have gone through and the road grime they've been exposed to. I'm not saying you wont' be able to get them off, but get ready for it to be a huge bitch."

breaker bar ftw

Quote :

"MARGINAL POWER GAINS"

FREE POWER GAINS

Quote :

"That's a pretty fucked up thing to do for such a minimal gain on a street car."

it's my understanding that many cars can pass a smog test without a cat installed if other emissions components are functional, which they are on this one to the best of my knowledge

I imagine it'd take a couple thousand catless Miatas in a decent state of tune to out-pollute a single old Buick burning oil sparking on 7 cylinders, but I don't see anybody getting all huffy about them... much less Chinese manufacturing polluting so bad runners are afraid to breathe the air... so why's this got a wad in yo junk

12/12/2008 4:13:12 PM

So hypothetically, if one owned a car without cats, how likely would it be that it wouldn't be noticed during a safety inspection (pre '96 vehicle)?

12/15/2008 12:11:23 PM

you should sell it to the street gangs that have been stealing people's CCs across the country

or is that an urban legend?

12/15/2008 12:17:48 PM

Quote :

"knock the catalyst out, its a honeycomb similar to ceramic"

on another note there is also a steel like brillow netting in the cat on some cars. its a pain in the ass. to get out and its between the to layers of the ceramic

12/15/2008 1:45:50 PM

Quote :

"street gangs that have been stealing people's CCs"

Quote :

"you should sell it to"

Does not compute.

Quote :

"I imagine it'd take a couple thousand catless Miatas in a decent state of tune to out-pollute a single old Buick burning oil sparking on 7 cylinders, but I don't see anybody getting all huffy about them... much less Chinese manufacturing polluting so bad runners are afraid to breathe the air... so why's this got a wad in yo junk"

It wouldn't be reasonable to destroy all the non-efficient cars in the name of conservation. It is reasonable to expect people to leave existing emissions devices in place and replace them when necessary if feasible.

[Edited on December 15, 2008 at 1:56 PM. Reason : l]

12/15/2008 1:54:26 PM

Quote :

"So hypothetically, if one owned a car without cats, how likely would it be that it wouldn't be noticed during a safety inspection (pre '96 vehicle)?"

its suppose to be routine procedure for an inspector to check for cats and pretty much every other thing.

so unless you know someone, or unless the inspector things you're cute, then they'll catch you.

some may not care if you have a resonator under there or some sort of bulge to make it look like a cat. i mean, they arent crawling under there to test it. its all visual.

12/15/2008 2:16:24 PM

resonator ftw

passed the old jetta at jiffy lube for three years in a row

12/15/2008 3:47:56 PM

How to:
Remove Cat

12/15/2008 5:30:37 PM

lol
i was waiting for something like that

12/15/2008 5:32:46 PM

I'm gonna be pissed if they don't look for the cats, have to pay $120 for 2 of them but I can get the boyfriend to weld them in so might as well go ahead and get them while I can get free labor.

12/18/2008 2:56:24 PM