Removal of 3 CATS and Resonator on 4.6 - TCCoA Forums
 
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post #1 of 13 (permalink) Old 05-21-2015, 05:57 PM Thread Starter
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Removal of 3 CATS and Resonator on 4.6

What if any would be the drawbacks of doing such? My car is no longer required to pass any emissions test, so no problems there. I'm just wondering if it is worth it. A trusted mechanic has told me he thinks I would be better off leaving the two front CATS and removing the third CAT and the resonator. My main objective is to help remove the drone at certain RPM. He told me I would have a racier tone with a higher note than the bass I currently have with Flowmaster 40s, which I intend to keep on the car.
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post #2 of 13 (permalink) Old 05-21-2015, 08:21 PM
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It is illegal to remove in all 50 states, even without emissions testing.
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post #3 of 13 (permalink) Old 05-21-2015, 09:19 PM
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No inspection and no testing pretty much relegates it to only illegal on paper.

-Matt
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post #4 of 13 (permalink) Old 05-22-2015, 08:14 AM
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unless you are replacing the whole exhaust system with a high performance
type system, leave it along.

I replaced on my 96 cougar, manifold to muffler with the parts from my 95 Cougar.
Kooks, 2 1/2" pipe and turbo mufflers.
The sound is great, quiet at idle and just enough roar.
NO drone.

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post #5 of 13 (permalink) Old 05-22-2015, 09:12 AM
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Removing the 3rd cat/resonator is not going to help the sound. Not much you can do to help Flowmasters.

Al

97 T-Bird LX 4.6 - 80k miles
94 Supra TT Auto - street/strip car
04 CVPI- Brenda's car - 76k miles
Previous Fords:
95 T-Bird LX 4.6 - fully optioned, owned 15 years, 220k miles
96 Cougar XR-7 4.6- Brenda's car, owned 11 years, 187k miles
88 T-Bird 3.8 - first T-Bird, owned 5 years, 206k miles
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post #6 of 13 (permalink) Old 05-22-2015, 08:07 PM
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id keep at least one cat so it doesn't stink
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post #7 of 13 (permalink) Old 05-24-2015, 05:24 PM
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With an EFI car removing the cats will actually hurt performance, as the sensors will be thrown way out of norm for readings, and with too little back pressure the 4.6L cannot breathe properly. Just put a cat back with larger pipes on.
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post #8 of 13 (permalink) Old 05-24-2015, 05:57 PM
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Quote:
Originally Posted by steveg1988 View Post
With an EFI car removing the cats will actually hurt performance, as the sensors will be thrown way out of norm for readings, and with too little back pressure the 4.6L cannot breathe properly. Just put a cat back with larger pipes on.
Umm, no.

-Matt
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post #9 of 13 (permalink) Old 05-24-2015, 06:47 PM Thread Starter
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I'll admit, after reading responses, I'm confused as to what is right and wrong. The simple thing to do would be to leave as is and replace the Flowmasters with stock mufflers, thus removing cabin drone when ascending/descending, which occurs in about 10-15% of my driving.

Thanks for the replies. I won't be making any changes for a while.
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post #10 of 13 (permalink) Old 05-27-2015, 03:27 PM
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Thrush makes inexpensive turbo mufflers that have a little tone to them while accelerating with no drone. Most parts stores carry them for around $50/ pair.
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post #11 of 13 (permalink) Old 05-27-2015, 03:53 PM Thread Starter
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Quote:
Originally Posted by blue95lx View Post
Thrush makes inexpensive turbo mufflers that have a little tone to them while accelerating with no drone. Most parts stores carry them for around $50/ pair.
Thanks, blue95lx, I appreciate the tip.
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post #12 of 13 (permalink) Old 05-27-2015, 04:49 PM
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Quote:
Originally Posted by XR7-4.6 View Post
Umm, no.
Only the rear sensors would be out of range - and set a DTC, but wont affect performance.

I do believe there is a downside to losing back pressure. If you unbolt the cat-back after the 3rd cat/resonator, there is definately a noticeable loss in power.
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post #13 of 13 (permalink) Old 05-28-2015, 08:11 AM
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+2, turbo mufflers.

Quickest N/A Modular MN12.
1995 XR7-11.77 @ 113.29 (3537 lbs.)
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