Sound-meter settings?

Hey all,

I was wondering what settings the sound meter is used in (slow/fast etc). I have the same one, and want to test on the same settings to ensure compliance. I've a noisy 90° V6 that needs a bit of work to get under 92dB. Also if anyone knows of local experts of quiet exhaust, please let me know.

Red 09 Yaris 5-dr. H-street/FSP
Black Seven (Caterham knockoff) E-mod
Silver 01 Miata STR


    edited November -1
    dBA setting, slow, 80-100 range.

    The largest circumference exhaust you can fit in place will be the quietest. (larger circumference out-trumps length.)

    We have tried 14"-17" long straight through mufflers on loud cars and they do not quieten enough.

    When you run a larger diameter (6" vs 4" round) but shorter you get quieter.

    For troublesome exhausts you cannot replace Burns (or Coast Fab) for light, REBUILDABLE units. Expensive up front cost, cheap to rebuild.

    Exhausts wear out over time. The hotter the setup ( turbo/high compression) the faster the packing breaks down.

    We rebuild turbo exhausts twice a year.

    N/A exhausts once a year.

    Benefit is quieter exhaust, and more hp. (tighter packing when new makes more hp.)
  • edited November -1
    Thanks for the info Don. I will keep it in mind. Currently I have sidepipes with 4"x22" straight-throughs and it is stupid loud. Maybe 40" of total length from collector to tip. I'm going to jam on some 4.25"x9.75"x28" two tube/partition mufflers and see what happens. I'm sure it will still be too loud. Winter I will shorten the headers to gain another 10" and try a second muffler as well. I hate the sound of the 90° V6 so quieter is better anyhow. If that still is over 92dB, I'll look into the expensive stuff. Interestingly enough, the OE car runs a fairly small muffler, with a 30" resonator (and cats) and they are really quiet. The induction noise may also be an issue, but I can barely hear it at this point over the exhaust.

    I was going to sound test today, but did a friend's car first which was much, MUCH quieter and was still 102dB. I didn't bother doing mine.

    I also got the answer to the settings question (Thanks Kevan).

    Red 09 Yaris 5-dr. H-street/FSP
    Black Seven (Caterham knockoff) E-mod
    Silver 01 Miata STR
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