I need my bike to meet 94db but the Q4 comes in much quieter.   Can I shorten it (looks better, lighter, better performance?)  and meet 94db?   How much?   

When you say Q4, do you mean FMF Q Stealth?


If you're talking Stealth, then yes, I believe you can trim the length somewhat. Disassemble the silencer and you will be surprised at how much of it is "empty".


Just remember that FMF made the Stealth as it is to meet their sound goals. In other words, it's long for good a reason.


If you want to know how much to trim to get a certain dB, trial & error (cuttng 1" off at a time) is about the only way anyone will know, short of contacting FMF.


Don't expect much weight loss or power gain, but it will look a ittle better.


Wouldn't it be easier to just get an old FMF Q?

Leave it. You will NOT notice any power from cutting a few inches off of it. Leave it just a tad quieter.

I'm sure you can shorten it if it's anything like every other silencer I've had apart.  You'll save some weight (little), it might look a little better, but chances are it will perform no better, possibly even worse.

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