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Thread: Muffler flow tests and Exhaust theory

  1. #21
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    I have that exact set of Borla ProXS mufflers used in that test on my car right now. I bought them for Anderson years ago. I'm quite happy with them. They are loud at WOT, but don't drone when cruising down the highway.
    1988 Thunderbird
    306 HO w/ A9P processor
    AOD w/ Transgo Reprogrammer
    MAC Offroad ProChamber w/ Dual Borla ProXS mufflers
    Full Digital Dash w/ twin Cyberdyne A-pillar gauges
    245/50/16 Tires on Snowflakes

  2. #22
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    An excellent question was asked in another thread.

    Quote Originally Posted by Grumbles View Post
    Will an H (or X) pipe installed AFTER the cats be as effective as one installed beforehand?
    EDIT: Sorry thread hijack.

    Here's a quote from a write-up I linked to above concerning that particular case:

    If, to stay legal your exhaust system must run catalytic converters, then the possibility of loosing power goes up dramatically, but it certainly does not mean the game is lost. The first rule of thumb here is if the cats must be in the original position, use the highest-flow components that can be physically installed. For high-flow, high-performance cats, one of the first places I would try would be Random Technologies. Some of this company's key employees drag race late model-street legal machines and are serious about performance. Also in the business of marketing genuine hi-flow cats and cat systems are Walker (Dynomax), Magnaflow, Dynatech and, for a number of specialized truck installations, Gale Banks. These are not the only ones, but they are all the companies of which I have experienced the no-nonsense functionality of their products.If the position of the cats can be moved to such an extent that the length going into the cats represent the secondary tuned length, then we find that to an extent, the cat, if large enough, can, in part, act as a resonator box. Moving the cats to a more favorable position then is rule number 2 when cats must be used.Rule number 3 is that if there is room to put a crossover or an X-pipe before the cats, then that's almost always the best place. Anything after the cats will drop the sound level but is unlikely to increase power unless the flow of the mufflers you chose was significantly short of what was needed.
    -- 05 Mustang GT-Whipplecharged !! -- 87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's! http://www.fquick.com/V8Demon

  3. #23
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    OK, I got rid of the 18" Magnaflows (anybody want them?) and switched to Corsa "Drone Buster" Mufflers. I must sadly report that they didn't reduce drone on my full 2 1/2" system using an off-road H-pipe.

    Part of the plan was to weld Catco's into the H-pipe to reduce odor and perhaps lower overall noise levels to some extent. I have a set of the Magnaflow high-cell density cats that can fit almost anywhere (only 4" diameter and 11" long) - I am now wondering if I could incorporate them into my flow tubes that go between the H-pipe & mufflers.

    Hmmmmmm....
    11.96 @ 118 MPH old 306 KB; 428W coming soon.

  4. #24
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    Quote Originally Posted by Cougar5.0 View Post
    Here's my favorite muffler shootout article - just the all-important comparison tables


    Those charts are all well and good, but how often are cars driven around the street, cruising at 5,500-6,700?
    If worms had daggers, birds wouldn't f**k with 'em

  5. #25
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    Quote Originally Posted by 88BlueBird View Post
    They are loud at WOT, but don't drone when cruising down the highway.
    Just do you guys know, mine drone...I picked them up based on comments like the above.

    1800rpm's and it sounds like I've got a subwoofer vibrating at whatever frequency it is (hard to estimate). If you see this, what does the underside of your car look like? Drone is an issue of resonant frequencies and the fact that both pipes being the same length will act like a tuning fork.

    The mufflers sound healthy enough from the outside, flow well, and should last just about forever.

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