Hey mate, I have a Tenere with the Kev mods & Akrapovic pipes but original foam filter.
Out the box the Akras arn't much louder than stock pipes, but I drilled out the holes I the end of the baffles a bit bigger as with them completely removed was a bit to loud. There was a small gain in performance & bear in mind they still have cat's in.
Most people I believe , if your handy with a welder or know someone who is, tend to cut out the cat's on the original silencer for better gas flow / engine note / fuel economy & performance.