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Magnaflow Exhaust Review (In-Progress, Pics Video Upcoming)

Discussion in 'Engine, Drivetrain, and Exhaust Discussion' started by ZyroXZ2, Jun 4, 2018.

  1. ZyroXZ2

    ZyroXZ2 United States Active Member

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    Hello everyone! New to the forums, first post, didn't want to waste the time with an introduction and just dive right into the good stuff we all know and love: modding!

    I received the first run of Magnaflow catback exhaust back on 5/31, and then FedEx gave me blue balls and had a strange delivery exception so it instead arrived on 6/1 despite being out for delivery on 5/31. :eek: I promptly put my rear tires up on ramps and jacked the front half up so that I could do a "ground" catback installation since I'm all by my lonesome but a fairly competent garage mechanic. Other than an RMA process I'm currently undergoing due to the exhaust being damaged (read: three dents; one big one on the driver side muffler and two tiny ones on the Helmholtz resonator on the passenger side) and my dumbass not inspecting it before slapping it on the car, I have enough miles on it to get a feel for what to expect when the glasspacking "settles" and it becomes louder.

    LOOKS:

    It looks a little "ricey", admittedly. I am thinking of fabbing up a "normal" plate bracket instead of their "mf" logo. The exhaust "tips", if you will, do not have the covering plate that the factory exhaust has nor are painted black like the factory exhaust. Thus, I painted the exhaust "tips" with black primer to hide them. Otherwise, the piping is very easy to see through the facia tips and it's a bit of an eyesore.

    SOUND:

    This is about a wash in terms of what's good and what's bad. The good is that the exhaust has no drone at cruising speeds whatsoever. In fact, the low tone "hum" is so mellow that you could easily mistake this for being factory exhaust. That is until you give the car medium engine load. This is somewhat RPM independent: you could give the car medium engine loads accelerating, but then be cruising at the same RPM at 80MPH and not even know you have an exhaust on the car since road/wind noise covers it up entirely. What happens at medium engine load? Resonance. The exhaust system resonates and is enough to vibrate the cabin. At this point, my giblets might have moistened up at the idea of going WOT. So I did. And it sounded like... stock. Yes, the exhaust system is quieter at WOT than it is at medium engine loads. The noise of the engine overwhelms the exhaust, and as a car enthusiast, that is all bad for an aftermarket exhaust. This concept is backwards: it should still be quiet at medium load, and then sing songs of thousands of explosions happening in my engine for the world behind me to hear at WOT. So, it's great that there's absolutely no drone, but it's all bad that it's louder at medium throttle due to resonance. As a final closing good note, though: if you wanted the "executive express" experience with an aftermarket exhaust, this one is essentially what you want... with the said exception of medium engine loads.

    Update - The glasspacking is finally beginning to settle and compact itself due to the moisture and heat of engine cycles and driving around. Thus, it's getting a bit louder and closer to its "nominal" state. With it being a little more loud, it does balance out the resonance by being louder overall so that the resonance doesn't stand out so much. This is a very tiny victory, though. I also decided to give it a quick WOT under a short overpass to listen to the echo off the walls, and it still sounds so close to stock I almost can't tell from inside the car. However, my schedule is pretty hectic and I'm awaiting an RMA replacement, so I still won't have sound clips for awhile as the new RMA replacement muffler will have to go through this same settling process before I record it.

    POWER:

    The torque power band does feel like it's changed. Instead of the factory slam-you-into-your-seat feel, it still plants you in place but does more of a build up to what seems to be a harder pull up top past 5k RPMs. That would make sense, of course: by doing a consistent piping diameter through perforated straight through mufflers, you effectively decrease back pressure which inherently shifts the torque curve upwards in the power band. Since the turbos can push more air out at higher volumes, the power increase would naturally be almost all top-end power. I'll continue to update this section as I keep driving it to compare.

    I know you all want pics and sound clips, and I will get those to you when I can. For now, I'm just giving a preliminary review of my experience with it.

    Stay tuned!... Get it?!... Okay maybe not, I'm waiting on touching the tuning until some time has been spent by hundreds of tuning shops because I don't want core component damage :geek:

    Update - Quick exhaust video posted just below. Used a lavalier mic and mounted on the rear fascia outside the vehicle and then again on the inside against the driver's side headrest.

     
    Last edited by a moderator: Jun 20, 2018
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  2. Kazz

    Kazz United States 1000 Posts Club!

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    Interesting! Thanks for the write-up!
     
  3. DiabloStinger

    DiabloStinger United States Active Member

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    Interesting on the medium load scenario. I had an R32 V6 that had an exhaust from Magnaflow... same issue. I really didn't mind because it was still slow AF. However, I agree that the angels should sing with the WOT requests.
     
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  4. ZyroXZ2

    ZyroXZ2 United States Active Member

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    Thanks! I'll be working on getting pics + video clips!

    What's strange is my old car (a Grand Prix GXP LS4, so a 5.3L V8) had a full downpipe + custom piping setup using Magnaflow parts (high flow cat, resonator, mufflers), and it sang quite well at WOT. I don't get why this thing decides to shut itself up when I tell it to start yelling angrily at everyone, but wants to be annoying when no one asked it to o_O
     
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  5. Kamauxx

    Kamauxx United States 1000 Posts Club!

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    Thanks for the review!

    Magnaflow was my first choice but I just couldn't wait.

    I wonder if it's more quiet at WOT because the gases are bypassing the hemholtz resonators more efficiently. The gases could POSSIBLY be bouncing around in the resonators while you're at mid-RPMs.
     
  6. ZyroXZ2

    ZyroXZ2 United States Active Member

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    Oh I'm sure it has everything to do with the Helmholtz resonators. My bet, though, is that it's less about airflow overall: the resonance comes from the particular volume of air passing over the piping leading to the resonator being just the same as what happens when you find that resonant airflow when you blow over the top of an open top bottle. A Helmholtz resonator is actually the same concept: just take an empty bottle, unscrew the top, and blow over the top at varying pressures and air flow until you get that resonant hum. That resonant hum is what I believe to be happening with the exhaust system at medium engine load. This has everything to do with engineering: I don't think this Helmholtz resonator was particularly and mathematically tuned for the 3.3L TT Lambda II engine.
     
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  7. Johnny B

    Johnny B Canada Member

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    Do you feel that the car is making more power with this exhaust?
     
  8. ZyroXZ2

    ZyroXZ2 United States Active Member

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    On the good ol' butt dyno, it was a pretty big leap in power that could range from 15-20HP. However, since that was late at night when the air was a nice and cool 65 degrees F, I decided I'd wait until the next day to test it. Well, the next day decided to be 85 degree weather and mild traffic so I haven't had an opportunity to corroborate my own butt dyno with a repeat. It DID feel more powerful, though, and Magnaflow is just a straight-through perforated core design. I haven't commented on "power" in my review, yet, because I haven't had a chance to do consistent runs on different days and conditions to compare to how it felt before. Of course, with the weather warming up day-by-day, I have no clue whether I can get a solid feel for it. I will update the thread as I gather pics, videos, etc., though!
     
  9. ZyroXZ2

    ZyroXZ2 United States Active Member

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    Just posting a little update since I decided I'd give it a little more juice today on my trip to get some brown rain lunch (read: Taco Bell).

    SOUND:

    Update - The glasspacking is finally beginning to settle and compact itself due to the moisture and heat of engine cycles and driving around. Thus, it's getting a bit louder and closer to its "nominal" state. With it being a little more loud, it does balance out the resonance by being louder overall so that the resonance doesn't stand out so much. This is a very tiny victory, though. I also decided to give it a quick WOT under a short overpass to listen to the echo off the walls, and it still sounds so close to stock I almost can't tell from inside the car. However, my schedule is pretty hectic and I'm awaiting an RMA replacement, so I still won't have sound clips for awhile as the new RMA replacement muffler will have to go through this same settling process before I record it.

    POWER:

    The torque power band does feel like it's changed. Instead of the factory slam-you-into-your-seat feel, it still plants you in place but does more of a build up to what seems to be a harder pull up top past 5k RPMs. That would make sense, of course: by doing a consistent piping diameter through perforated straight through mufflers, you effectively decrease back pressure which inherently shifts the torque curve upwards in the power band. Since the turbos can push more air out at higher volumes, the power increase would naturally be almost all top-end power. I'll continue to update this section as I keep driving it to compare.
     
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  10. soulevo8

    soulevo8 United States Active Member

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    Out with the old, in with the new. I don't have much more to add to this very thorough review. Install is simple. It took me about an hour in my garage. The sound really isn't much different from stock, which is what I want. I plan on getting downpipes next and I think that will bring the sound up right where I want it. I'm not getting any medium load resonance like you described either.
     

    Attached Files:

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  11. ZyroXZ2

    ZyroXZ2 United States Active Member

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    Hmmm, well I am due to look over it again to make sure nothing went loose on me, so I'll check for exhaust leaks or something, though I didn't hear any when I first installed it :eek:
     
  12. soulevo8

    soulevo8 United States Active Member

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    One thing you might check that I noticed.... the flange that bolts to the downpipe has slotted holes. There was enough wiggle room that the mid pipe could possibly block a bit of airflow
     
  13. ZyroXZ2

    ZyroXZ2 United States Active Member

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    I did notice that, too, but I centered those best I could. Besides, that wouldn't cause resonance, that would just kill, like, 0.7HP :p
     
  14. ZyroXZ2

    ZyroXZ2 United States Active Member

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    So I visited my muffler shop of 15 years, and he let me put it up on the rack so he could check for exhaust leaks. I revved it plenty and other than him making the joke, "is it even on?" (which is what he does for any exhaust that isn't on a small block V8 or bigger that shakes the walls), he said he doesn't hear or feel any exhaust leaks... Not sure why I have resonance and you don't, though. It's physics, and maybe you and I have different definitions of "resonance" :rofl:
     
  15. Ozstung

    Ozstung Australia Stinger Enthusiast Sustaining Member

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    Sounded more than reasonable I thought, not overboard but still sporty. You'd be happy with that?
     
  16. ZyroXZ2

    ZyroXZ2 United States Active Member

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    "Happy" is pushing it: I would like a properly engineered system so that there is no mid-throttle resonance but is louder at WOT and doesn't have some lousy, un-aerodynamic advertising nameplate; but I'm overall satisfied so far :p
     
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  17. Ozstung

    Ozstung Australia Stinger Enthusiast Sustaining Member

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    My experience with Aust Bimodial exhaust was similar. Had two test drives resonance to me was most similar. But thats just my view.
     
  18. ZyroXZ2

    ZyroXZ2 United States Active Member

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    We need throttle activated exhaust butterflies. I don't want to have to flick a switch (or in the Australian's case, changing to Sport mode with this exhaust wired up) on a whim because not flicking it means decreased power on demand. Sometimes I just gotta get on the gas and make that merge or exit, and I ain't go no time for fussin' with a switch :D
     
  19. robz32

    robz32 United States 1000 Posts Club! Staff Member Moderator

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    What you are referring to is an RPM trigger for the butterfly. There are some exhaust that have this feature already. One of them is the Bastuk.
     
  20. KLR STINGER

    KLR STINGER Canada Active Member

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    Thanks for the detailed write up and follow up video. I've got the Magnaflow on order, and will be mating it with the Jun BL down pipes. I wonder if that combo will be a tad more aggressive. One though I had was doing a 2.5" hole saw cut into the end of the Helmholtz resonator, and welding on a flange for an electric cut out. That might give it a bit more sound. You could use the Varex smartbox controller to program the opening to your liking. It connects to OBD2 port and will open and close based on TPS, RPM and speed. You can also geo-fence it in quiet mode ( ie cold starts at home not to annoy neighbors. check it out: Varex Smart Box
     
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