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Thread: Do catalytic converters affect exhaust sound?

  1. #1
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    Do catalytic converters affect exhaust sound?

    Just as the title asks...i want to know if running cats or running w/o them affects the exhaust note.

    If you wanna know why:

    I want to free up the exhaust on a budget...kinda. I heard the conbination of hi-flo cats>big resonator>no mufflers....and I liked it, but right now i think i dont have enough for the cats...so i might run just a pair of Wynn's 2 1/4 downtubes into a large (very large) resonator and straight pipes out the back...so im wondering if the sound will differ from what i heard. In case this doesnt please me or it gets too loud/annoying i might consider adding cats....OR...could i add another resonator...like have two back to back?
    Current: 1993 SC 5.0L Auto Red, 1994 SC 5-speed Teal, 1995 SC 5-speed Chameleon Blue
    Old: 89 SC auto Twilight Blue, 89 SC stick Titanium, 90 35th stick, 92 Sport 5.0L stick, 94 SC stick Black, 1994 SC Auto Teal
    Also: 1992 Feature Mustang Convertible 5-speed Vibrant Red, 1991 BMW 850i 6-speed Red, 1994 BMW 850CSi 6-speed Red

    www.mamn12.com for your mid-atlantic mn12 needs!

  2. #2
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    Yes...since removing my high flow cats about a month ago it's considerably louder and sounds a little more raspy/tinny at WOT. BTW, It doesn't appear to make any more power than it did with the cats on.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat...............707HP/650TQ

    My Garage

  3. #3
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    Y Cats?

    Unless your state requires cats, Why use them at all?

    Dual 2.5" down pipes, 2 in, 1 out Resonator, 3" or 3.5" single center pipe, & then split out to dual 2.5" turbo muffs. You'll pick up a LOT of flow, & the resonator will keep the "buzz-ies" outa the car.

    I have headers, 2.5" down pipes, NO cats, NO resonator, 3.5" center section, & dual turbo muffs. It gets Extremely buzzy when I'm racing. It's not a problem for ME, but it annoys the hell outa the guy who lost the race.

    68COUGAR

  4. #4
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    I like my exhaust 2 1/4 duals no cat or res. just two little mufflers. If I could get away with it I would not even run mufflers.

  5. #5
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    I think i should be able to get the exhaust in a few weeks. I guess in the mean time ill start with the 2 1/4 downtubes from Wynn and a big resonator with no mufflers. I need to get rid of a few things first to get the $. Altho im pretty sure i can get away with running no cats im still unsure as to how it will sound. Anybody have any sound clips? If need be I can always add hi flow cats...that set up i've heard and I like.


    ....mmmmmm....then i can add the smaller 89-93 pulley for some free HP!
    Last edited by CaifanSC; 07-11-2005 at 11:52 PM.
    Current: 1993 SC 5.0L Auto Red, 1994 SC 5-speed Teal, 1995 SC 5-speed Chameleon Blue
    Old: 89 SC auto Twilight Blue, 89 SC stick Titanium, 90 35th stick, 92 Sport 5.0L stick, 94 SC stick Black, 1994 SC Auto Teal
    Also: 1992 Feature Mustang Convertible 5-speed Vibrant Red, 1991 BMW 850i 6-speed Red, 1994 BMW 850CSi 6-speed Red

    www.mamn12.com for your mid-atlantic mn12 needs!

  6. #6
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    Re: Sound Clips

    Quote Originally Posted by CaifanSC
    Anybody have any sound clips?
    The problem with sound clips is that there is no standard by which to make them. Also no standard procedure for making in car sound clips.

    Personally I think that the standard should be the same as measureing home speakers, 1 meter (39") on axis, with a flat freq. mic. Course, how many people have even a mediocre mic, let alone a good flat mic? Same goes for the recorder & media. Recorders run the freq. response gambit from abysmal to studio quality. Same for the recording media. Some tape is barely adequate for answering machines, some others can reproduce sounds that only bats can hear. Digital recorders? Again, how many people own a Good Quality dig. recorder (Sony DTC-57) AND know how to use it properly? OK, so a good compander could be used to tame the input levels to the dig. recorder, but if you don't use a compatible compander on play back, the sound will not be accurate. So much for recording. Lets say that everything is PERFECT on the recording end. How are you going to listen to the sound clips, on a pr. of $30 computer speakers? Nuff Said!

    68COUGAR

  7. #7
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    In plain english..... I guess you shouldn't try to even bother doing a sound clip

    Frit

  8. #8
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    Califan, ... I still have cat's on my car. But they are cleared out. .. And it actually adds to the rumbling I think. .. Because the air get's to the cat & it almost sounds like it rumbles around in there before leaving. .. I have the SCP exhaust with hollow cats & it sounds like a 60's muscle car.

    Anthony

  9. #9
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    hey guys, on my 89sc i have the flowmaster force 2 with a resonator delete, i was thinking about gettin the drag pipes w/o cats off texas thunderbirds, but anyway would it change my exhaust note any? i like how it sounds now but i dont need it get any rice tone, will it just make it louder?
    any input helps

  10. #10
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    Hate to say this, there is no way of getting a V8 sound from a V6.......

    Just ain't gonna happen......

    sure you may get the idle to "sound" like one but once the revs come up.... forget it...........

    So the ways I figure it..... get a nice free flowing exhaust, but keep it quiet, then let the blower do the walking and talking

    Frit

  11. #11
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    Why run cats? Because they greatly reduce the amount of VOCs that are emmitted from your tailpipes. VOCs are nasty to breath.

    Yes, CATs definately make your exhaust sound different.

    I just had a guy at the gas station today say "whoa dude, that car sounds sick! (that means cool) is it fast?" My exhaust sounds VERY cool in my opinion. It doesn't sound like a V8, but it's still very cool. I'm running long tube headers, 2 1/2 into 3" back into 2 1/2 and then through Summit Turbo mufflers. No cats (shame on me). It's a 89-91 setup. (for sale by the way)

  12. #12
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    what do you guys think of just running the flowmasters for now, mostly stock piping, just the 2.5's off the manifolds. will it sound decent? i dont mind how it sounds now with the cats

  13. #13
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    Without cats it will buzz when you get on it...it will sound fine when your at idle..

  14. #14
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    ekk buzz as in rice buzz? if so will the hi flo cats be ok

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