You are correct about the headers being the restriction. You can go the way RoLoo has gone and remove the cat.
BTW this is Akra's claim by means of a dyno print. It is apparently rwhp. Note the increase in torque. Now that is "real world" usable power that is shown. I do not use the high rpm range most of the time on the road, only when on the track.
During the last track day at Kyalami, they did a noise test at 4,000rpm and got a 93dB. Limit for the day was 110dB. So, it is really not too loud.
The custom design for the R12S by Akrapovic also make the rear end of the bike look slimmer. The dual can layout is in my opinion a bit dated.
Cheers
