Useless Muffler Statistics

I just got a stock baffle for my stock muffler on my '99. (I bought the bike used and it didn't come with one.) I've been running an FMF Megamax II for the past year and a half because it had a quiet core insert when I needed to run quieter.

Here's some useless statistics for those who are interested:

<ul type="square">[*]Stock muffler with baffle weighs 8-1/2 pounds [*]FMF Megamax II with quiet core, freshly packed weighs 6-1/4 pounds

Noise level measurements:

Stock muffler, baffle in

<ul type="square">[*]Idle: 81 dBA [*]1/2 to 3/4 throttle: 92 dBA

Stock muffler, baffle out

<ul type="square">[*]Idle: 91 dBA [*]1/2 to 3/4 throttle: 110 dBA

FMF Megamax II, 8 disks, quiet core in

<ul type="square">[*]Idle: 86 dBA [*]1/2 to 3/4 throttle: 94 dBA

All sound level measurements were taken with a sound level meter set at A-weighting, slow response, and was positioned 20 inches away from the exhaust outlet at a 45° angle.

This was my first ride with the stock baffle in- I was amazed at how quiet it was and the power wasn't too bad. You can really hear the engine noise with the exhaust that quiet. I'll use it when I'm at an event where sound levels are an issue. (Leaner jetting may help with the power there.) Otherwise, the FMF muffler will stay as my first choice because even with the quiet core removed, it's quieter than the stock muffler without the baffle. (I didn't measure the sound level without the FMF quiet core because it was getting dark and I didn't want to piss the neighbors off, but it's definitely quieter.)

I found these very interesting, not manufacturer claim but real word numbers

Not useless but definitely "USEFULL" stats

anyone have same kind of number for stock YZ silencer?

thanks for posting these


Good job Rich,

I too would like stock YZ info..


It just so happens that I'm riding with a dude with a YZ426 with a stock pipe and muffler this weekend. I'll report my findings in the next few days.

Hey Rich, come out and race the Mims Hare Scrambles!! You're twice as fast as you were the first time we dragged you to a race :)

When is it? This weekend, the WDSRC is doing a dual-sport ride both days in Ocala, so I'm booked Saturday and Sunday. But I may be able to if it's in the next few weekends. BTW, let's not bring up my one and only hare scramble experience. :) Looking back, I guess I can at least claim a small victory in that I didn't crash in that huge mud pit in front of all the spectators. And that I didn't puke. (Disclaimer: Neither did Josh.) But I gotta find some bright side to my dismal performance that day.

YZ426 with stock pipe and muffler

<ul type="square">[*]Idle: 94 dBA[*]1/2 to 3/4 throttle: 106 dBA

Thanks Rich,

I believe the new Calif. regs. top allowed is 102db?..Can anybody answer that?


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