FMF VS Pro circuit

I have a sound meter and this sunday my 250f with full pc exhaust was 98 db's at idle and 110 at around 1/4 to 1/2 throttle!!! My friends totally stock 03 crf450 was 88 db's at idle and about 95 - 97 at 1/4 - 1/2 throttle.

The current AMA test is to test a bike at 20 in from the rear of the silencer with the bike operating at half its maximum rpm's. There is no way that any of the pipes in that test will be under 110 at 6750 rpms.

Agree with you. Some of us have bought our own sound meters and we CAN NOT get to that sound level unless the bike is idle - at idle my PC4 is already at 100 DBs! :D

I don't understand how they can claim 102 or 105 DBs even at 5,500 RPM (not to mention at 6,750)... :)

I will read the article closely when I get home to see how they got these answers, but here is another interesting article those fine-riding Aussies have put together. They note in there that the "freshly packed" exhausts were way quieter than the "not so freshly packed" ones.

just another interesting pipe-noise article, check it:

the bottom of the article at:

also notes what RPM they used and at what distance (the testing measures used).

Anyone have an M4 on their 250F? Is it at as loud as the space shuttle? :) I hope not!

OK, just one last post, and that's that I'm home, looking at the Dirt Rider article, and it doesn't specify the testing measure used to get these readings. However, it does say:

"Not so long ago Dirt Rider assembled a complete exhaust test with Yamaha's '00 YZ426F (August '00 issue). The results revealed that although some aftermarket exhaust systems developed performance in certain areas, very few outdid the stock unit throughout the power curve. Now we have the YZ250F, Yamaha's newest four-stroke masterpiece. As with the YZ426F, we expected slight gains or shifts in power, but nothing like the metamorphosis we experienced. Several of the systems were the first pieces to come off the assembly line or were still works in progress; yet every combination made gains in performance and overall horsepower."




Sound was a compromise to build performance: The stock unit metered at 100 decibels while aftermarket systems ranged from 102 to 105 decibels. We did take into consideration that these systems were designed for close-course competition only, but some of the louder units were a little much on the eardrum, even with a helmet on."

Might I ask this....what is the best exhaust that will alow me to ride OHV areas? Spark Arrestor and low noise are requirements.

Probably the only viable option is the FMF Q. I saw one on ebay and asked the guy how quiet it is and said almost at the stock wr level.

According to the link posted by tangwhl - an 01 YZ426F with the "FMF Powercore Q Series" got 100 DBs (the "standard" YZF pipe listed there is 101 DBs), the stock WR silencer is much quieter. Many of the tests were done on 2/13/2001 according to the bottom of the page but the page was updated last on 7/20/2002 - so the newer Q may be quieter than the one they tested.

Some TTers are running a recent version of the Q, can any of you guys do a sound check on it using a Radio Shack sound meter? Everyone seems to be wanting a quiet silencer such as the Q but we don't have any real measurements from TTers.

When making sound measurements it is important to ensure that you have switched your noise meter to the "A" (general noise) scale. Many meters automatically set to the "C" scale (music) when powered on. A noise meter set to the "C" scale will give an inaccurate (high) measurement when measuring an motorcycle exhaust.

As for the test dates on the page. When new models come along that are different enough to warrant taking note of, we measure and post them to the page. Word came out recently of a new model FMF 'FIM Legal' muffler. As soon as this appears you can be sure that we will test it and publish the results.

I would probably go with the fmf or the stock pipe i like the stock pipe on the 2003 250f which is what i have.

The way I look at it is if you want to increase power to your bike, the easiest way to do this is to get an aftermarket exhaust sys. The only problem is that if you want to be legal at 96db the only way to there is to have a stock system with an insert in. Even the FMF-Q is going to put you at around 100dbs, so for 3 more dbs get a sys that will greatly improve power everywhere. I have the TI-4 on my bike and really like it, the FMF Ti is supposed to be good too. I wish that I could get a chance to try them all but I don't have that luxury (s?). I think my pipe is around 103dbs, I wish it was quieter but I really like the power it gives and I only ride my bike on a closed course. The stocker is a good pipe too....


I'm waiting on the P-Bomb header for the Q which supposingly should drop the DB's alittle more than just the silencer itself.

And if you add the New End Cap and insert it lowers sound alittle more by 1.5 db's. So the end should be around 96 or less------> So I hope.

The FMF-Q is still in the box waiting cause it doesn't just slip on the stock header.I thought it did. :)

Oh yeah>> Big Gun is supposed to have one too.

BIG_FAT_&_SLOW - How about posting that PC/FMF comparo? Have you gotten around to it yet? I personally have the FMF (And love it), but my brother is still looking and I'm interested to hear the difference. Thanks

Scratch my last post. I must have been on the bong or somthen. (just a metaphore) The PC Ti system is about $100 cheaper and that is for the full system. No mid pipe no nothen. Do a sear on Rocky Mountain and you will find out.

M3. I never got to it. Sold the FMF as soon as I got it. Our association is implementing sound testing this year and neither would have passed. I can tell you that I rode my bike with the pc and a friends WR with all the free mods expcept yz timing. He has the sx header and pcIV silencer. Between the two I would buy the pc. It had a lot more snap and low end. I couldn't believe the difference. Sorry I don't throw on my Ti4 when I got it.


Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now