pros and cons on removing cats

Discussion in '2005+ Mustang GT 4.6L Tech' started by Johnstone, Jun 18, 2019.

  1. Johnstone

    Johnstone forum member

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    I recently discovered that one of my cats were finished. anyone here remove there's cats?
    how bad does it smell? any significant power added?

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  2. Macman45

    Macman45 Resident Geriatric

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    Finished as in no good? I removed mine years ago and love it. It's LOUD but I enjoy it. Probably 8ish HP, not a ton. You will need a good tune or MIL eliminators or you'll have a Check Engine for the O2 sensor. Smell is not bad at all I dont think, you cant smell it in the car and have to be behind it for awhile to notice
     
  3. MrAwesome987

    MrAwesome987 forum member

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    Mine is MUCH louder without the cats, and it does smell a bit at stop lights, but its not that big a deal to me. The power gain is negligible. The most annoying part for me was the CEL was on for the o2 sensors. Beware, bama and other email tuners won't disable the CEL (although they can, they just won't). I ended up living with the CEL for months until I got the car dyno tuned.
     
  4. Johnstone

    Johnstone forum member

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    yea melted and clogged. either I get a used set of cats or go HPipe
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  5. MrAwesome987

    MrAwesome987 forum member

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    Also, the exhaust is much raspier without cats.
     
  6. tjm73

    tjm73 of Omicron Persei 8 S197 Team Member

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    Where do you live? Do you have to pass inspection? Will you be able to pass inspection without the cats? In NY you would be VERY hard pressed to get a sticker saying you passed. In fact you have to have the OEM to pass inspection. In NY you would have to replace the entire midpipe at around $1600.
     
  7. Johnstone

    Johnstone forum member

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    I'm in Montreal. unless u get pulled over and asked to pass inspection that's not really a problem since I have friends at the inspect center. I'm more concerned with the smell and annoying loudness.. I have a supercharger on and I do push the car from time to time
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  8. MrAwesome987

    MrAwesome987 forum member

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    Mine has pypes headers, no cats, and Mac mufflers and is extremely loud in and outside of the car. If you are concerned about loudness at all, I would suggest putting the cats back, or looking for some really quiet mufflers.
     
  9. Johnstone

    Johnstone forum member

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    I have Borlas touring and they sound awsome but it isnt that loud.. I'd go a notch or two higher. I'll see, I'm leaning towards no cats.
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  10. MrAwesome987

    MrAwesome987 forum member

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    Ok one more comment and I'll shut up lol. You mentioned you have a supercharger; can you hear it? I have a blower on mine and I can't even hear it until about 5k rpm because of the exhaust, which was a bit disappointing. Not trying to talk you out of losing the cats, just hoping to help you make an informed decision.
     
  11. Johnstone

    Johnstone forum member

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    lol yea I hear that sweet whine quite well actually. thanks for the input
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  12. RLF9409

    RLF9409 My blood runs Ford blue!

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    I had to put cats back on mine. It was to raspy and created a trumpting around 2k rpm that i couldn't stand. Also I hated the smell of exhaust on my clothes after driving.

    2006 Saleen SC #409 MMR 1000S stroked 4.6 3.0 pulley 1 piece driveshaft
     
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  13. 06 T-RED S/C GT

    06 T-RED S/C GT forum member

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    I ran catless for over 2 years with just Borla S Type mufflers and Mac O/R ProChamber. I really loved how loud the Borlas sounded with the windows down, but the drone was just too much to deal with especially when the windows are up. The smell, however, wasn't really that bad from inside the car. Recently, I added the ProChamber with the OEM catted downpipes to find out if that would help reduce the droning issues from the Borla S Type mufflers. Needless to say, when pairing the ProChamber with the stock cats, it did nothing more than just reduce the overall volume of the exhaust, but does absolutely nothing for reducing interior resonance drone. IMHO it appears the ProChamber only amplifies and deepens the amount of drone when paired with a straight thru design muffler such as Borla and is much better suited for a chambered design muffler such as Mac and Flowmaster. At any rate, I recently ordered an after cat X mid pipe from Pypes Performance Exhaust that I'll be adding to the stock cats and Borla Atak mufflers that I recently purchased from Ron whose also a forum member here on S197 forums. I also decided to keep the OEM cats in place just in order to avoid any potential raspiness and trumpeting issues. In the meantime, I'm hoping that by making the switch from the ProChamber to catted X will give back the overall sound volume that was lost and also make a noticeable improvement in reducing the interior resonance drone as well. That being said, I suppose we'll find out soon enough :shrug:
     
    Last edited: Jun 19, 2019
  14. Johnstone

    Johnstone forum member

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    all the things you hate is what I'm trying to avoid as well.
    today I gave the go ahead to put back the cats.. I cant deal with the drone.. I cruise alot with it when with the kids and wife so last thing I want to hear is them nagging me about the sound..lol
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  15. 06 T-RED S/C GT

    06 T-RED S/C GT forum member

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    I hear you and know exactly where you're coming from. I even considered looking into going with a high-flow catted H mid pipe from Pypes Performance, but IMO I really don't think high-flow cats do much of anything for reducing resonance drone over the stock cats and with no cats at all, just amplify the frequencies that produce resonance drone that much louder. Anyway, my reasons for not being able to deal with drone, is most of my cruising is on the highway between 1800-2200 RPM in 5th gear at 55-65MPH when the drone is at its worst, although once I climb up to 70 MPH and above is when I'm finally out of the drone zone, but when just driving around town, the drone is just as bad as well. So now that I'm running Borla Ataks, I know beyond a doubt that without cats, the exhaust would be way too loud, raspy and trumpeting, especially when paired together with an X mid pipe lol.
     
    Last edited: Jun 19, 2019
  16. Johnstone

    Johnstone forum member

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    I even had put wool in the trunk under the spare tire.. surprisingly helped. the Borlas I got are grea, nice deep tone but at low rpms they resonate a little.. but hey it's a mustang not a Cadillac lol
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  17. Pentalab

    Pentalab forum member

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    Is it true that Montreal is the pot hole capital of North America ?
     
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  18. Johnstone

    Johnstone forum member

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    oh yea.. it's a fk disaster in some parts
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  19. 06monera96

    06monera96 LeShawno

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    I dont miss Montreal one bit other than insurance was cheap and so was cost of living.
    But everytime I return to visit my family my stang would get damaged LoL
    Was born in Cote des neige in 86 moved to Park X by 89 and moved away to ShitHole Toronto by 2005.
     
  20. Johnstone

    Johnstone forum member

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    yea I guess it's not for everyone.. i love Montreal despite the imperfections.

    but have to admit Toronto roads are really nice.
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