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FFCOBRA MASTERCRAFTSMAN 5626
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3,860 Posts
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Is a cat converted needed? I'm using a 93' Cobra engine. I'm being told that back pressure is needed to make her run properly. Is this true?

Thanks,
Albert
 

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Junior Charter Member
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289 Posts
You can run without cats no problem, but be sure and check on the registration/emissions process in your area, you may need them for that. Running W/O them will not hurt the engine the headers and side pipes provide plenty of back pressure.
 

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FFCobra Fanatic
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3,751 Posts
Hey Talbert, I'm part of the mustang cobra doner club too! I ran cats for 6+ years and took them off a year ago when I pulled the smog equipment off. The car runs fine with or without them.
 

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FFCobra Fanatic
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12,975 Posts
Cat is only used for emissions to help burn the remaining fuel that the engine can't. Has no real effect on how the motor runs other then what come out the tail pipe. Most hi po cat's have less restriction then a oem cat does. you will need them to get past emmisions if tested.
 

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Senior Member
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3,217 Posts
If you have them, hold on to them. Other than the emissions part, the other big reason that folks use them is to quiet down the exhaust. They do make a big difference and the loss of HP is minimal. Loud obnoxious sounding sidepipes are really cool for short trips around town, but if you make any longer trips, you'll appreciate the difference the Cats make.
 

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Junior Charter Member
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I can't speak from direct experience, but my neighbor put cats back on his '90 Mustang to pass NH inspection. He said he noticed that the exhaust stink disappeared after the cats were put on. This may be another positive reason to use cats.
 

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835 Posts
If you add the cats, do you have to run the air pump too? I think I heard something along the lines that you need the extra air to get the catalytic process to start.

??
 

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FFCobra Fanatic
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4,257 Posts
I have cats for sound reduction and have run for 6 years without an air pump. Works fine.
 

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Junior Charter Member
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Originally posted by DL:
If you add the cats, do you have to run the air pump too? I think I heard something along the lines that you need the extra air to get the catalytic process to start.

??
Injecting air from an EGR makes the cats burn hotter - like blowing on hot embers - stoking the fire makes things burn hotter. After the engine reaches operating temp. - the cats go to work. I think light-off for cats is around 550-degrees. Late model converters flow very well because of the honeycomb internals. OEM converters are built much more HD than aftermarket ones - never chuck the OEM converters. they are built to last 8 years / 100,000 miles. Aftermarket cats are built to last 2 years/24,000.
 

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Premium Member
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365 Posts
I like the idea of running cats. Kill two birds with one stone, help the environment, and quiet down the tone,,...... My idea is the cut out the old cats from my H pipe, and weld them into exact place on the FFR J pipes.
I know that FF sell the catted J pipes, however for the cost savings, I'd thought I'd give it a go.....
Any postive or negaitve feedback?
 
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