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#253189 - 01/05/18 02:38 AM running no cat exhaust ?  
Joined: Feb 2015
Posts: 5
G-Rage Offline
Rookie Poster
G-Rage  Offline
Rookie Poster

Joined: Feb 2015
Posts: 5
Pearland, TX
I've seen many folks here running 3" exhaust with no cat.
What will deleting the cat do anything to engine behavior?
I'm guessing with no post cat O2 it should not be an issue huh?

I've not seen any such advice or maybe my search skills suck....?

Thanks and looking forward to feedback.

Last edited by G-Rage; 01/05/18 02:55 AM. Reason: duh moment !

Bird is the word...
#253190 - 01/05/18 10:43 AM Re: running no cat exhaust ? [Re: G-Rage]  
Joined: Feb 2013
Posts: 72
squeeky Offline
Boosting 5 psi
squeeky  Offline
Boosting 5 psi

Joined: Feb 2013
Posts: 72
north carolina
I bet half the people on here are running with no cat, I have been 3" into 2.5" duel for about 4 years now and no problems what so ever......... : )


88 turbocoupe, gillis valve, k&n, short throw shifter,3" exhaust with magnaflows,Garrett(turbonetics) T3,AFPR,18lbs boost for now.....
#253191 - 01/05/18 02:10 PM Re: running no cat exhaust ? [Re: G-Rage]  
Joined: Apr 2001
Posts: 2,537
BJL Offline
BJL  Offline



Joined: Apr 2001
Posts: 2,537
Sewell , New Jersey
been 7 years for me with no cat. even passed emissions on its own a few times before i went with historic tags.


Brian J Larkin
88TC "Turbo II" Owned 10 years. 312k miles
T3, 3in stinger exhaust, gillis, 255 walbro, afpr, 5spd swap,spec clutch, sn95 5 lug, k/n,
89 Cougar XR7 3.8SC Auto
95 Ranger Splash 3.0 auto
http://s9.photobucket.com/user/BJL88TC/m...a20d48.jpg.html
#253192 - 01/05/18 02:12 PM Re: running no cat exhaust ? [Re: G-Rage]  
Joined: Apr 2001
Posts: 9,339
Jeff K Offline
NATO President
Jeff K  Offline
NATO President

Joined: Apr 2001
Posts: 9,339
Milwaukee, WI
Gutted my cat years ago when the state stopped emissions testing cars from earlier than the 1996 model year. I left the empty cat in place so it looks like it is still there. Not much seat of the pants improvement, but without the cat, the exhaust system has to flow better, FYI, I have a 3" DP going into two 2.5" pipes with straight thru mufflers.


Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
#253197 - 01/09/18 07:56 AM Re: running no cat exhaust ? [Re: G-Rage]  
Joined: Feb 2015
Posts: 224
anasazi4st Offline
Boosting 10 psi
anasazi4st  Offline
Boosting 10 psi

Joined: Feb 2015
Posts: 224
Phoenix, AZ
Hmmpf. And I just bought a universal catalytic converter, was going to install it myself soon. After 10 years the one Meineke installed started to break up into chunks, the pieces rattling around noise caused me considerable alarm until I figured out what it was. I removed the exhaust pipe and pretty well gutted the cat to eliminate that.

I remember when it was almost as bad here in Phoenix as LA...if you went up into the mountains around here about 20 years ago you could see an ugly tan haze over the city on some days. They’ve done a wonderful job in getting rid of that, so I would bet there’s no way I could pass Emissions here without a working converter. Still, the retest is free if I fail the first time....


1987 Turbo Coupe w/T5OD, 8.8 axle, grey smoke; most options. Bought in 1991 with 41K miles: 3 turbos, 2 heater cores, 1 tranny swap (and now a full rebuild), 5 clutches, 1 head gasket, 2 Teves II ABS units, etc. later....
#253295 - 02/13/18 04:11 PM Re: running no cat exhaust ? [Re: G-Rage]  
Joined: Dec 2001
Posts: 29
niteshooter Offline
Boosting 5 psi
niteshooter  Offline
Boosting 5 psi

Joined: Dec 2001
Posts: 29
Toronto Ontario Canada
Yup have an empty shell under mine. Back in the mid 90's I started to find little metal balls on the driveway, car always passed it's emissions tests even though I was told the cat was hollow as it had blown out all it's contents. I've just left the hollow shell under there, even when I finally replaced the muffler when it went a few years ago.

Since then the car has no longer been required to pass an e-test. One thing I will say is that your exhaust smells a lot more without the cat so for some that might be a reason to have it, otherwise I honestly didn't notice much difference performance wise. I did once I replaced the stock muffler with a Borla, plus it sounds better.


86 Turbo Coupe
86 Jeep CJ7
77 Thunderbird

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