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Thread: I can hardly think with all this DRONE...

  1. #1
    Join Date
    Apr 2002
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    Howell, NJ
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    I can hardly think with all this DRONE...

    Or maybe it's just an overall loud exhaust.

    The new '94 SC I picked up seems to have that loud exhaust drone/sound all the time except maybe while coasting. I need some help figuring out how to decide what to do first in an attempt to improve/ eliminate it.

    New custom 2.5, 3.0, 2.5: Kooks mid length headers, no cats, custom down tubes (one with wideband o2 bung), 18" Magnaflow resonator, Magnaflow 15" mufflers, tailpipes in stock configuration. The exhaust is nicely done, with flanges at the end of the headers and at the resonator.

    Just too loud inside while driving. From what I understand, longer mufflers and straight back tailpipes can help with the exhaust noise. But these rear bumpers/valences are not very conducive to that. I don't like the look of straight tailpipes coming through, or sitting under the bumper. I chose a compromise on my 90 where a "halfmoon" was cut out from the bottom and the tailpipes came out straight under that. Just don't like the idea of cutting into a nice rear bumper cover...

    My buddy suggested having small resonators installed where the cats would have been.

    Any ideas about how I should proceed? It just kills me that this brand new, custom exhaust now needs to be hacked into to try and quiet it down. But it really is too loud inside the car.

  2. #2
    Join Date
    Jul 2004
    Location
    Hamilton NJ
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    Lets see a pic of the exhaust Joe,
    Tom Downs-member#2752
    MPX'd 90 SC Auto~bought Feb. 2012
    RIP MOM!!! I will always miss and think about you 4Ever! 1940-2018
    RIP Rexy boy!!!! Miss my dog 2006-2018
    http://www.sccoa.com/forums/garage_v...vehicle&id=424

  3. #3
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    Lol, I was under the car on my back an hour ago thinking it would be nice to have it up on a lift to get a few pics of it...

  4. #4
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    Quote Originally Posted by joenintiesc View Post
    My buddy suggested having small resonators installed where the cats would have been.
    That, or a pair of cats, will quiet it down quite a bit.

  5. #5
    Join Date
    Feb 2009
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    Mount Vernon, WA
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    Dynomax VT

    I had 2.25 down pipes into magnaflow 2.5 dual in/out 2.5 true duals into magnafow big case mufflers. Had annoying drone 1700-2300. Front seat not too bad, but only short drives for anybody in the back. Car sounded good in cab, but not so good outside when under acceleration. Resonator blew out all packing so replaced with x pipe and dual mag resonators. Only a little drop in drone, but car sounded like a goose with its head in a vice. So after reading about Dynomax VT mufflers I figured what the hell. They Sound awesome and No Drone! Been on the car for a year and still sounding good. Highly recommend these for drone and good sound.

  6. #6
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    Easiest thing is to replace the 15" magnaflows with some Dynomax super turbo's. Basically a straight through muffler (like Magnaflow) without cats is going to be loud. Even the 18" are going to be marginal out back, and unless the pipes are already run at a 45 deg angle, they won't fit without a bunch of cutting.

    The turbo style mufflers are chambered to make the muffler seem like it's 2x as long which increases dampening, but ONLY if they also have packing in them. A chambered muffler without packing will be too loud. For example, the Thrush turbo's are hollow except for their chambers, and are way too loud. The Thrush Hush series is chambered and has packing. I don't necessarily recommend those, just saying they have chambers + packing. There are other better options. The turbo style muffler is an economical way of getting more muffling into the same 15" space occupied by the Magnaflows.

    On the other hand, you could also just add cats to it. Then it would be quieter and less stinky. lol
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  7. #7
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    One more vote for putting cats on it. I had blown out cats on my 90, and after installing a new pair, it drastically reduced the amount of drone. My setup is true dual 2.5", ported manifolds into custom downtubes, a pair of high-flow cats, then into an x-pipe, then a magnaflow DIDO muffler, then out to a pair of Thrush chambered mufflers out back. It is still a little too loud/droney for my tastes, but it is tolerable now to where I can take the car on a 2 hour drive and not be miserable by the time I get there. With the old blown out cats, anything more than an hour and I was starting to get a headache from the drone. My next step will be to replace the thrush mufflers out back with something quieter, but I have too many other projects, so for now I'm OK with it. If you're in Howell, you're only about 20 minutes from me, so if you want to take a ride in mine for comparison, shoot me a PM and we can meet up some time.

  8. #8
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    Thanks for the replies. Aren't cats going to be more expensive than resonators that would go where the cats would be? Is that what is making all the racket - the sound of the exhaust flowing though the headers pretty much right below and forward of me in drivers seat?

    Or is it the exhaust going through the straight through muffler and then bouncing off the ground and back up at the car.

    I was looking at those Dynomax VT's based on that other thread and they intrigued me, but at the same time the Dynomax Super Turbo's are certainly a lot cheaper. Cheap and works good is what I'm after...

  9. #9
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    Quote Originally Posted by MadMikeyL View Post
    One more vote for putting cats on it. I had blown out cats on my 90, and after installing a new pair, it drastically reduced the amount of drone. My setup is true dual 2.5", ported manifolds into custom downtubes, a pair of high-flow cats, then into an x-pipe, then a magnaflow DIDO muffler, then out to a pair of Thrush chambered mufflers out back. It is still a little too loud/droney for my tastes, but it is tolerable now to where I can take the car on a 2 hour drive and not be miserable by the time I get there. With the old blown out cats, anything more than an hour and I was starting to get a headache from the drone. My next step will be to replace the thrush mufflers out back with something quieter, but I have too many other projects, so for now I'm OK with it. If you're in Howell, you're only about 20 minutes from me, so if you want to take a ride in mine for comparison, shoot me a PM and we can meet up some time.
    Thanks, that sounds like an idea, plus it would be nice to meet my fellow SC neighbors!

  10. #10
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    Still thinking about the cat side, Dynomax Bullets are cheaper than a cat, but the Ultra Flow Rounds are aprox. the same price as the Magnaflow Hi-flow cats...

  11. #11
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    It's definitely the exit sound that is bothering you. Make sure the tips extend below the bumper cover. If they are too short it will cause the sound to reverberate back into the car.

    You certainly can try the bullets, they will help. Not sure how much though since I haven't tried it on an application like yours. I once used bullets as a resonator and that worked ok as I recall but it's been a long time.
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  12. #12
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    Thanks Dave! I will start at the back end then.

  13. #13
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    Cats can be had pretty cheap.

    http://www.ebay.com/itm/2-5-Inlet-Ou...cca853&vxp=mtr

    Not only will the cats do more to quiet it down compared to some bullet mufflers, but then you won't have to worry about anything come inspection time.

  14. #14
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    Quote Originally Posted by MadMikeyL View Post
    Cats can be had pretty cheap.

    http://www.ebay.com/itm/2-5-Inlet-Ou...cca853&vxp=mtr

    Not only will the cats do more to quiet it down compared to some bullet mufflers, but then you won't have to worry about anything come inspection time.
    I applied for a collector car voucher (already have collector status for my 90), so I will be exempt from emissions inspections. That said, does the 'hi-flow' cat flow as well as a bullet muffler? If I were to put cats back on, where does the LC1 o2 bung go? Right now it is smack in the middle of the down tube... I guess if they both flow the same and are in the same ballpark $$ wise, I would lean toward the cats if they are quieter. But I am still going to look at a different muffler and tailpipe configuration first.

    I am going to take it to Mufflex to get an idea about costs. They seem to be he only custom exhaust shop in the central nj area.

  15. #15
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    The spun metallic core cats flow very well, more than most mufflers, but they suck as cats and they don't do much to the sound for the same reason. A ceramic brick style cat will work much better and the flow really isn't that much of an issue.

    For example, I took standard cats off my wife's stock SC and put on the metallic core cats. It went from barely registering on the emissions test to barely passing, no other changes.

    On the other hand, Phil's car makes 400rwhp, relatively serious cam, has standard brick cats, and passes much cleaner than the wife's stock SC. Both are tuned properly, of course.

    This is an example of the type of cat I recommend.

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    http://www.summitracing.com/parts/cto-6906/overview/
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

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