Mid-range chugging problem ...

What do you mean by chugging? Is the missfiring, feel like a cylinder not firing? if it is change the plugs.

plugs usually last me 12,000km or 6000miles

I wouldnt say misfiring .. it just seems to be lunging in between 6 and 8 rpm .. its not backfiring or anything .. the plugs were changed in april last year. And the bike has only got 8400 kms on it now ..
I m going to tear it apart and pull the plugs, change the fuel filter and clean the air filter .. hoping that helps things. Maybe run some seafoam thru the system too to be on the safe side ....

check the gap of the plugs , just to rule the plugs out.

Well ill check the condition of the plugs when i pull them too. I went today and got new plugs .. (ouch) and a new fuel filter .. and i m going to spray down the carbs with some cleaner just in case too ...

Ill pull the bike apart later this week and cross my fingers that it goes away ..

What year is your bike? I've got an 01 and was having the same problem. The bike would kinda hesitate a little if I kept it at a constant 5-7 g rpms but if I got on the throttle it wasn't there. I didn't really think too much about it because I had my bike dynoed and nothing out of the ordinary showed up. I figured it was the infamous "flat spot" that the R6's were famous for. I put an ignition advancer and velocity stacks on it this year and the problem seems to have disappeared. I'm not sure what was causing it, but I'm glad it's gone. The bike runs silky smooth now :thumbup . Hope this helps a little...

Oh yeah, I changed the plugs out last year and that didn't help at all so save yourself the time and $$. I also had the carbs synched at a dealership before I put in the velocity stacks and that didn't help the problem much, either.

6-8 k isnt really in the powerband is it? mine doesnt start pulling till around 9 or 10 revs, but mine also redlines at 16,500 too so who knows. I got an 00 by the way.