I was told the Vinci X3 violates the db scale at 102db's at 4500 rpm at 1m!! That is LOUD and will definitely piss off the local USFS rangers...even if the pipe does have an approved spark screen.
I was told the FMF Q is being discontinued. Knowing a few folks that have that set of cans, the quality is not great, basically you get what you pay for. The exhaust pulse of the big bore v-twin tends to blow out the packing pretty quickly and the spark screen gets burned up after only 4-5 days of hard riding. The good news however is that FMF has developed a new 950 can called the Ti Q. No screen to burn up as it uses a USFS approved turbine arrestor that is claimed to be a lifetime design. The Ti can is also lighter weight and runs cooler than the original aluminum skinned Q. Not sure if the new model will offer longer lasting packing. They do claim it meets 96db sound limit required by USFS, in fact it meets this limit with a couple db's to spare yet blows as free at top end as the Akra's.
Frankly, most dyno's I've see on this bike show very little is gained performance wise by a can, the bike just runs much cooler, loses at least 10lbs up high and you get a USFS approved spark arrestor...at least in case of FMF, though not w/Akra, Staintune or Remus. The only downside to new FMF is the price: $899. Still less than Akra but for low mass, lifetime spark arrestor, reduced heat, not too loud exhaust note and hopefully good durability, it seems well priced. Again, you get what you pay for. Take care