DBa rating on the YZ450F

I would like to race an enduro event next month but need my 450 to meet the noise requiement. Does anyone know what the DBa level is of the stock YZ450F?

Has anyone bought the quiet tip for the promotobillet spark arrestor? I was hoping to go with the PMB $150 dollar S/A quiet tip combo opposed to the FMF Q-muffler at $300.

Additionally, any ideas what the DBa level is on the 450 with the PMB SA and quiet tip?

Any help appreciated... :)

i have heard the fmf power bomb header works like a little muffler too and take a fe DB out.


I had my 450 tested at hollister.I tested 96db 20" out with just the PMB sparky.I am going this sat and can do another test to make sure it was tested correctly.I'll let you know if it changes. :)


Please repost your DBa results when available.

It's a shame to get rid of the titanium end cap. I put a PMB in my 02 426 and the quiet core drops the db's quite a bit. I haven't ridden with it yet so I don't know how much power it will suck up. I talked to Terry at PMB and he said they haven't done any sound tests on the YZF's yet but the CR450 was down to 96 db's. Which race are you going to do? I'm gonna race the D36 race at Wileysville in November. I wanted to race the Lilliputan at Hangtown in a few weeks but seperated my shoulder at Hangtown 2 weeks ago. What db's are they looking for? I have heard they want 100 db's but I have also read that now they want 96 db's. I hope the PMB gets it low enough to pass the D36 sound check.

Let me know when your going riding and we can hook up. On second thought, I swore I would give my shoulder till the end of the month before I rode again. After that, I'm game.


Oh yeah, about the FMF Q silencer. I had one but wound up sending it back for a few reasons. First off, it kept hitting my rear brake caliper when I would bottom the rear suspension. The joint where the header and silencer connect also had pretty good exhaust blow by. FMF told me to use thread tape and hi temp silicone as a sealant, neither worked. I also dreaded taking that thing on and off because the mounting clamp was atleast a 2 person job. The performance wasn't bad but I thought they needed to do some additional engineering work on it. They may have since then, I don't know.

another problem with fmf quietcore is it sticks out to far. first time you loop out, it gets torn off or broken it half.


I think the enduro is on the weekend of Nov 24th somewhere near Stoneyford. My buddy is into the D36 enduros and talked me into riding this race. He received a flyer on the event - I think they are calling it a family enduro? I race MX and this would be my first enduro. I am a little concerned with 450's 1.8 gallon tank running out of petrol.

The D36 rules state the DBa should be 99 but my bud said they were testing for 101 at the last race. Either way I hope the PMB will work.

I will probably ride out at Hantown next week on Wed practice. #26

Keep in touch on the enduro..

i tested again and was at 96.4-97.4. So you should pass no problem. :)

I was there when Blue tested I can vouch for it, I saw the whole darn thing I was a witness I can prove.

Ok I said it Blue thats 20 bucks ya owe me :)

Awesome! thanks for the info. I'll order the PMB S/A.

I will keep you posted on enduro schedule for Nov. I ride tracks all over northern CA so if you see #26 on a YZ450F stop by and say hello.


The Blue One,

What rpm did you take the reading at? The test rpm has not been published for the 450 yet, but in a pinch I would guess that any testing person/official would get a next best temporary substitute value of using the spec for the 02 426 - 4500 rpm. The readings are very rpm sensitive and testing at the correct rpm is key to passing the test.

It was at 4500 just like the 426.

The Blue One,

What rpm did you take the reading at? The test rpm has not been published for the 450 yet, but in a pinch I would guess that any testing person/official would get a next best temporary substitute value of using the spec for the 02 426 - 4500 rpm. The readings are very rpm sensitive and testing at the correct rpm is key to passing the test.

How do they determine the RPM to do the testing at? It seems very subjective.

How are the sound wars going out there in CA....Are the sound police out in force at every event as was threatened earlier this summer?

Bonzai :)

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