• Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech

Removing a cat or two? or four?...

  • Thread starter Thread starter ACSPONY
  • Start date Start date Dec 6, 2004

ACSPONY

20+ Year Stangneter
Oct 10, 2004
711
2
19
Ohio
Dec 6, 2004
#1
  • Dec 6, 2004
  • #1
Noticed my 97GT has 6 cats....wtf-thank you Ford..
Has anyone ever removed 4 of the cats? Will the car pass emissions with only two on each side? Most all of the other cars I've ever seen only have 2, not 6...
Another question-Do high flow cats do just as good a job with the 2 as the factory 6? Like how bout a BBK or something catted x.

~A.C.
 

Bill9000

Member
Oct 15, 2004
182
0
16
Dec 6, 2004
#2
  • Dec 6, 2004
  • #2
well I dunno what would pass smog or not, but I looked under my car when I bought it, and said the same thing!!!! WTF!!!!

there are 4 cats, the other two little "cans" are resonaters of some sort. but still, 4 cats!!!! sheesh!

I'd do an off-road H-pipe, and keep the stock one, use it for passing a test, then bolt in the new one, it's not a very difficult thing to bolt in and out... (well it'd be worth it to me anyway! I can't stand catrs, they rob horsepower, kill gas mileage, stink when they go bad, and cost a lot of money!!!
 
0

01TrueBlueCobra

New Member
Feb 16, 2004
336
1
0
somewhere
Dec 6, 2004
#3
  • Dec 6, 2004
  • #3
Bill9000 said:
well I dunno what would pass smog or not, but I looked under my car when I bought it, and said the same thing!!!! WTF!!!!

there are 4 cats, the other two little "cans" are resonaters of some sort. but still, 4 cats!!!! sheesh!

I'd do an off-road H-pipe, and keep the stock one, use it for passing a test, then bolt in the new one, it's not a very difficult thing to bolt in and out... (well it'd be worth it to me anyway! I can't stand catrs, they rob horsepower, kill gas mileage, stink when they go bad, and cost a lot of money!!!
Click to expand...
Like he said , but if you really want Cats get a magnaflow X-pipe w/2 cats. Afriend of mine has a 98GT and he put on a magnaflow X-pipe w/cats and still passes emissions. The key is to do a oil change and run some fuel system cleaner before your test and always drive your car for about 20min before you goin for the test , because you want your cats to be hot and at operating temp, going in with cold cats is bad.
 

Blev

New Member
Aug 17, 2003
1,295
1
0
So. Cal. V-Town
Dec 6, 2004
#4
  • Dec 6, 2004
  • #4
I have been told by numerous people that the Magnaflow catted X will pass the sniffer but fail visual. That's why I went with it instead of the Bassani X
 
B

bdcardinal

tree hugger
Jun 10, 2003
3,612
16
69
santa barbara, CA
Dec 6, 2004
#5
  • Dec 6, 2004
  • #5
ya at my work, blev knows where i work, the only midpipe on a 96 mustang that we will pass is the OEM one with all cats. in CA it is illegal to modify or remove cats on a OBD2 vehicle.
 

tomustang

Psychotic Member
Founding Member
Jun 8, 2000
3,434
2
78
McLean Hospital
Dec 6, 2004
#6
  • Dec 6, 2004
  • #6
ACSPONY said:
Noticed my 97GT has 6 cats....wtf-thank you Ford..
Has anyone ever removed 4 of the cats? Will the car pass emissions with only two on each side? Most all of the other cars I've ever seen only have 2, not 6...
Another question-Do high flow cats do just as good a job with the 2 as the factory 6? Like how bout a BBK or something catted x.

~A.C.
Click to expand...

it's illegal to remove any cats from the car best option is to get an offroad h-pipe for like $100 and keep the stocker so you can switch upon inspection. but removing 4 cats does sound unique
 

BlackMach2

New Member
Dec 3, 2004
15
0
0
Mass
Dec 7, 2004
#7
  • Dec 7, 2004
  • #7
For cars 96 and up in my state, no sniffer is put into the exhaust pipe, all they do is connect to the stock OBDII port and it checks for a "Check Engine" codes. I'm told that as long as the O2 sensors see a 50% reduction between the front and rear O2's, no "Check Engine" code is transmitted, hence you pass emissions.

As far as visual inspections, IF the inspector does ever stick his head under my car, he WILL see my two cats connected to my MRT H-pipe. I highly doubt the average inspector knows newer Mustangs have 4 cats, as long as he see's cat's I'm sure it won't go any father than that.

One last thing, if they do ever notice you have 2 cats instead of 4, all you have to say is the stock H-pipe was damaged by: a rock/tree branch/small farm animal, whatever. It's not against the law to replace a damaged stock H-pipe so long as you replace it with one that has cats & is 50 state legal. Check out this site for Cali:

"A legal aftermarket catalyst is one that is listed in an ARB approved manufacturers catalogue for the year, make, model, and engine size of vehicle on which it is being installed. Manufacturers of aftermarket catalytic converters must obtain an Executive Order for their products from the Air Resources Board in order to be listed in an approved catalogue."

http://www.arb.ca.gov/msprog/aftermkt/aftermkt.htm
 

Black Stang 97

the guy on top of me is funny
Nov 11, 2004
483
0
0
Los Angeles, CA
Dec 7, 2004
#8
  • Dec 7, 2004
  • #8
I also have a 97 GT and i went to get 2 of my cats taken off, the guy told me the car wasnt gonna run well because the sensors were not gonna read right or something, and that the check engine light was gonna turn on. is it true??
 
B

bdcardinal

tree hugger
Jun 10, 2003
3,612
16
69
santa barbara, CA
Dec 7, 2004
#9
  • Dec 7, 2004
  • #9
according to the BAR there is only one company that sells approved cats for OBD2 vehicles for Ford. also the vehicle must have a damaged midpipe.

Black Stang: it is illegal for you to modify or remove any of your 6 cats. in CA the only legal midpipe is the OEM one with all of the cats on it, wether it be 4 or 6. if you take an aftermarket midpipe to a shop and they install it they can be fined up to $10,000 for modifying a catalytic converter.
 

BlackenedSVT

Active Member
Jan 18, 2004
1,841
7
38
New Jersey
Dec 7, 2004
#10
  • Dec 7, 2004
  • #10
ACSPONY said:
Noticed my 97GT has 6 cats....wtf-thank you Ford..
Has anyone ever removed 4 of the cats? Will the car pass emissions with only two on each side? Most all of the other cars I've ever seen only have 2, not 6...
Another question-Do high flow cats do just as good a job with the 2 as the factory 6? Like how bout a BBK or something catted x.

~A.C.
Click to expand...

I had a 98GT and the only cats i noticed where the two cats that came on my MAC H-pipe. Never saw *6* or even *4* cats under there...maybe i'm missing something. Cause i only saw 2 on the H-pipe...unless there were "4" in that housing...

Makes me wonder what my new 02 GT has...maybe like 18 cats?
 

BlackenedSVT

Active Member
Jan 18, 2004
1,841
7
38
New Jersey
Dec 7, 2004
#11
  • Dec 7, 2004
  • #11
Black Stang 97 said:
I also have a 97 GT and i went to get 2 of my cats taken off, the guy told me the car wasnt gonna run well because the sensors were not gonna read right or something, and that the check engine light was gonna turn on. is it true??
Click to expand...

Yeah if you mess with the cats, like getting an off road H-pipe with no cats...then it will trip the check engine light. Thats why you need to get MIL Eliminators that come with most aftermarket H-pipes. This will let you use the H-pipe without tripping the check engine light, because the MILS bypass the light.

As for performance. The Off road H-pipe will give you more HP, but the cats do help with the backpressure to the exhaust that you will not be getting with the H. So your exhaust should be more snappy and poppy. Shouldn't really be a problem.
 

boomshack

New Member
Jun 4, 2004
274
0
0
Southern Cali
Dec 7, 2004
#12
  • Dec 7, 2004
  • #12
:OT: bdcardinal, rant buddy, you and JonJon have the BEST avatars!...that episode was one of the best I've seen in the last year...those guys are geniuses...they ripped here apart...okay sorry for highjacking...

BTW, these types of questions will never end...the reason : many mustang owners want that loud performance sound that a catback or welded-in aftermarket mufflers alone can't provide. You love your new Flowmasters/Magnaflows/Dynomax/MRT/Spintech/Warlock/Hooker/Bassani/SLP/Borla setup until you hear a sick-as-hell stang pass by you and realize that you want to be just as loud (in my case louder)...but Johny Law has decided that you can;t do it and sleep well at night...do it and forever look over your shoulders...
 
B

bdcardinal

tree hugger
Jun 10, 2003
3,612
16
69
santa barbara, CA
Dec 7, 2004
#13
  • Dec 7, 2004
  • #13
ya people just have to remember that offroad midpipes are sold for "offroad use only" by putting one on your vehicle you unoffically agree to only drive it off public roads, ie on a racetrack.
 

ACSPONY

20+ Year Stangneter
Oct 10, 2004
711
2
19
Ohio
Dec 7, 2004
#14
  • Dec 7, 2004
  • #14
Ok so I can't just take them off, it sounds like my best bet is to go with an aftermarket midpipe with cats? And say that the stocker got messed up on a speedbump..or something to that effect? Or, last resort of going with an o/r x or h and watching out for the po-po all the time?
 

jmk97GT

Member
Oct 29, 2004
178
0
16
Dec 7, 2004
#15
  • Dec 7, 2004
  • #15
Its not worth taking them off - trust me. Get a new midpipe.

I have the same problem...except my midpipe actually IS damaged (I have a feeling the previous owner took the car into a ditch ). When i changed my trans and rear end oil i noticed some branches and weeds and stuff stuck under there and one side of my midpipe hangs down...but the mounts are perfectly sound.

Anyways back to the topic...I have found that Bassani and Pypes catted x-pipes are both certified 50 STATE LEGAL. I personally am probably going to buy the Bassani this spring. Also thinking about which catback I want to get...not sure yet.
 
B

bdcardinal

tree hugger
Jun 10, 2003
3,612
16
69
santa barbara, CA
Dec 7, 2004
#16
  • Dec 7, 2004
  • #16
bassani is not legal for use in CA on 96+ cars unless you can prove that your stock pipe is damaged and you out of the CA required 8 year 100k mile emissions warrenty. if you are within the warrenty then you have to use a new OEM pipe. same goes for Pypes. unless the cats they use are made by TWC then they are not legal in CA. thats the only company i could find with CARB approved cats for Ford passenger vehicles.
 
0

01TrueBlueCobra

New Member
Feb 16, 2004
336
1
0
somewhere
Dec 7, 2004
#17
  • Dec 7, 2004
  • #17
ACSPONY said:
Ok so I can't just take them off, it sounds like my best bet is to go with an aftermarket midpipe with cats? And say that the stocker got messed up on a speedbump..or something to that effect? Or, last resort of going with an o/r x or h and watching out for the po-po all the time?[/QUO

First off you don't live in California , the most emissions anal state in the planet. So stop listening to those people from California telling you its not legal in cali. Second I agree get an aftermarket midpipe with 2 cats which is better then your 4-6 cats you have right now. Last time I remember the Magnaflow pipe passes the sniffer test. Inspection wise most states just plug a device into your OBD2 port. If you are still worried keep your stock pipe and put it in whenever its time for you to get a test. It only takes 30min to put it back on, thats what I do. Why is there so much DRAMA.
Click to expand...
 

Bill9000

Member
Oct 15, 2004
182
0
16
Dec 7, 2004
#18
  • Dec 7, 2004
  • #18
First off you don't live in California , the most emissions anal state in the planet. So stop listening to those people from California telling you its not legal in cali. Second I agree get an aftermarket midpipe with 2 cats which is better then your 4-6 cats you have right now. Last time I remember the Magnaflow pipe passes the sniffer test. Inspection wise most states just plug a device into your OBD2 port. If you are still worried keep your stock pipe and put it in whenever its time for you to get a test. It only takes 30min to put it back on, thats what I do. Why is there so much DRAMA.
Click to expand...

What he said. I agree 110% it's not hard to put the stock one back in temporarily.
 

ACSPONY

20+ Year Stangneter
Oct 10, 2004
711
2
19
Ohio
Dec 7, 2004
#19
  • Dec 7, 2004
  • #19
Thanks Bill and TrueblueCobra, I think a Magnaflow catted midpipe and magnapack catback would be a sweet set-up. And hanging on to the stocker is a good idea.
~A.C.
 
0

01TrueBlueCobra

New Member
Feb 16, 2004
336
1
0
somewhere
Dec 8, 2004
#20
  • Dec 8, 2004
  • #20
ACSPONY said:
Thanks Bill and TrueblueCobra, I think a Magnaflow catted midpipe and magnapack catback would be a sweet set-up. And hanging on to the stocker is a good idea.
~A.C.
Click to expand...


That combination will sound awesome. Its allways wise to keep the stock midpipe even if your state has no emissions testing. You never know when you might have to move to a state that does. Do your self a favor don't ever move to California. The reason I'm here is , because I'm in the military. One more thing when you put the stocker back on for the test make sure you run it for a 100 miles and drive the car for 20mins before you take the car for the test, That way the cats will be at operating temp .
 
You must log in or register to reply here.

Similar threads

C
Exhaust 4 Cats required for smog in California?
  • Codosuarus
  • Sep 28, 2025
  • Fox 5.0 Mustang Tech
Replies
11
Views
1K
Fox 5.0 Mustang Tech Oct 6, 2025
Scottyding73
S
Fox BBK X-pipe replacement Cat?
  • TIGGER
  • Aug 26, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
7
Views
377
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Aug 26, 2025
AeroCoupe
K
Resolved Weird sound coming from a freshly rebuilt 5.0L
  • karhoot
  • Jun 24, 2026
  • Fox 5.0 Mustang Tech
Replies
7
Views
380
Fox 5.0 Mustang Tech Jun 27, 2026
Mac131
Engine Random Misfire at idle.
  • Gulftown980x
  • Jul 29, 2026
  • SN95 4.6L Mustang Tech
Replies
11
Views
593
SN95 4.6L Mustang Tech Jul 31, 2026
squeak93
G
In expensive ceramic coating
  • gray owl
  • Jul 12, 2026
  • Mustang Sound & Shine All
Replies
7
Views
448
Mustang Sound & Shine All Aug 18, 2026
NotaVegetarian
N
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?