Sorry, should've said that was at 3/4 max revs, so about 4.5K rpm on mine. I thought it was a bit quiet as well, but I've done my own tests with two different track-day spec noise meters and they all came out the same. It really is surprising how much noise the bungs do remove from the exhaust, but if you consider that every 3dB is a doubling in volume, then without bungs the K1 is over 5 times louder