Wow, that is one tiny pass for all that air to go through.

I experienced very different problems with exhaust and DB killers when I come back to my R1 from 2005.
( I know its a different bike, but just to show you that it matters )

Went from bone stock to a catremover and aftermarket exhaust, it changed the power so bad that powerwheelies were hard to archieve.
got a PC3 and tuned it and it was running like a rocket.
Than I put the db killers in it that was blocking like yours. it had a hard time to ride properly when you took off at the traffic lights, just way to much pressure.

I modified my DB killer by drilling much more holes and the problem was solved! sound was way louder too.


What I would do if I were you: open up your exhaust by removing the popnails ( don't know if thats correct english ) and see if you can replace the Original 'sound reducing foam/cotton' ( if its allready there ) with better ones. When you have done that the standard DB killer should do his job just like the hard one. its a bit of work but well worth it