Exhaust running non smog cats

foxbodybill89

Member
Jan 19, 2020
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Sioux Falls, SD
I'm putting new exhaust on my 89, and thinking of getting an off-road x-pipe and having modern 3 way non-smog cats welded into them. All of the available catted midpipes have smog cats, but my rebuilt smog pump already sounds like :poo: after a couple months and I would like to remove the system but still have cats. But, as I understand the modern cats can run without smog because modern engine computers run cleaner and have downstream O2 sensors. I'm wondering how well modern cats will work with just the stock ECU and O2 setup.
 
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Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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I asked Bassani this question and they replied that the air pump was not needed with their High-Flow cats.

If oyu look at the picture of the product, the air pump tube from the air pump connects to the pipe after the cats, meaning it's pretty much useless for them, so I deleted my pump setup. I'm running cats because I can't stand the smell of off-road exhaust. For some reason it really bothers me.

Obviously, you want to make sure the car is running in a good state of tune. If it's not, you run the risk of ruining a pricey set of cats.

1604330340179.png
 
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foxbodybill89

Member
Jan 19, 2020
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Sioux Falls, SD
Well I did notice that on theirs... I'll be using a BBK midpipe with their long tubes and their smog tubes do go into the middle of the cats. But I'm thinking of going with a couple of Magnaflow weld-in cats into a BBK off-road pipe so no smog tubing at all. The car runs great, my thought was if you keep it in a good state of tune you can take a chance that it will run clean enough with no downstream O2's.
 

JMGlasgow

Mustang Master
Feb 19, 2017
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OBD1 cars don't have downstream O2 sensors. They only have the O2 sensors before the cats.
 

foxbodybill89

Member
Jan 19, 2020
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Sioux Falls, SD
Yes I know, my point being I'm wanting to use modern cats designed for that type of system on a car without them, unless it will significantly shorten the life of the cats.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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You won't get a straight answer. The fox doesn't have the proper system to monitor the efficiency of the cats and can make adjustments. They best you can do is "get it close" and hope for the best.

As long as you aren't running pig rich, you should be fine. But i can guarantee that only as much as i can guarantee there is water on Uranus.
 

Willybill32

Active Member
Jul 16, 2019
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Lexington, KY
I asked Bassani this question and they replied that the air pump was not needed with their High-Flow cats.

If oyu look at the picture of the product, the air pump tube from the air pump connects to the pipe after the cats, meaning it's pretty much useless for them, so I deleted my pump setup. I'm running cats because I can't stand the smell of off-road exhaust. For some reason it really bothers me.

Obviously, you want to make sure the car is running in a good state of tune. If it's not, you run the risk of ruining a pricey set of cats.

1604330340179.png
I, too, have the Bassani exhaust mid-pipe with the cats on my ‘86. My smog pump died years ago, and when my engine was out last year, all the air pump hardware and Thermactor lines came off. I plugged the line on the Bassani mid-pipe to the Thermactor tubing at the point six or eight inches from the X-section. It runs fine that way.
 
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Steel1

Mustang Master
Aug 18, 2017
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I used to rum my 93 with smog pump removed and a catted Pypes X , worked great , passed emissions every time.
Thankfully my car is now emissions exempt.
 
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foxbodybill89

Member
Jan 19, 2020
27
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Sioux Falls, SD
I decided to go with the welded in Magnaflows and eliminate the smog system as I stated before, the car runs perfect and I only drive about 4000 miles a year. Think I will run a bottle of Cataclean through it yearly also, will try to remember to update with results/progress. Thanks all