depends on the riding you do... out is awesome, but if your doing a big day 3/400 miles or a weekend / week away put them in - it'll do you bloody head in after 8 hours!!!!!!
Definately depends on exhaust make. I have always ran with baffle out until my current exhaust - Leo Vince GP Pro 2. It is too loud with baffle out - its loud with it in! (and I like loud)
I run a Yoshimura R77 with the baffle out but thought would try with it in to see what the difference is.... But attempting to put the baffle in, the retaining screw dropped in between the inner and outer casing !! What a sh*t place to put the access screw hole right where the bleeding swing arm is !!! So now the exhaust has to come off to retrieve the dropped screw . . . clearly would have been to easy to have the access screw at the bottom of the can !!! Not a happy bunny .......
Pain in the arse that bolt, I contacted akra they said the alignment was impossible! Hunts Manchester mechanic told me blade will adjust the fueling once the baffle is out so no problems. Not sure how true this is? Move runs fine if anything the slight hesitation it had at 6.5 rpm has gone.
Out. If you're a sensitive soul, or on a long run, get some Professional Hearing Protection from Hearwave Technology earplugs. Unless you're doing a trackday