It took some doing but I finally put this video together comparing the stock exhaust to the FMF Q4.

All in all I'm pleased considering I have few video skills. But it's all about the sound, and the sound is good.

I just wrote a big 'ol post on it at my blog and don't feel like writing all the details again. If you're interested in the nerdy stuff, the original sound files (youtube may have degraded them some) you can find it there.

KLX250S Stock Exhaust vs FMF Q4 | Out RecordingKLX250S Stock Exhaust vs FMF Q4

But I will put up the rough numbers:

..................Stock..........Q4.......Difference
Idle............65dBA........74dBA........+9
2000rpm.....71dBA........83dBA.......+12
5000rpm.....81dBA........93dBA.......+12
8000rpm.....90.5dBA.....96.5dBA.....+6

...keeping in mind all this was hardly scientific or conclusive. Just one guy having fun.

Here's the vid. Watch at the highest setting if possible:

https://youtu.be/EywT9uzMWhs

And if anyone knows how to embed a video here, please let me know. The youtube embed code doesn't work.

 

WELL DONE!

I'm sure this will be useful to anyone considering the purchase of the Q4 exhaust.

 

FWIW, I also have a FMF Q4. It was too loud for me with the stock head pipe. I put a Chinese eBay clone powebomb header on my KLX and it cut the sound right down.

I needed to take it to a muffler shop and get the end flared but it fits fine now and makes it much quieter.

 

Great job! I also have a Q4 and it was a bit loud for me so I opted to install a Quiet Core insert and its a lot better. I used an app on my phone, I know...probably not as good, but, assuming the app worked consistently it went from 96-97ish to about 89-91 db. Which is A LOT quieter but still really thumpy. I noticed above 40mph when the wind noise really picks up I can almost hear more engine noise over exhaust noise at that point. I love it. Now when I'm holding a gear up a long hill just to maintain speed doesn't seem like I'm trying to speed or haul *** either.

 

So as-is that pipe won't fit? What was the problem with it? Also build quality, what's your opinion?