Just for information, when I was at Evolve last week Sal thought my exhaust was quite loud... so using the works SPL meter I measured it a 6,000 rpm, 0.5m away at 45 degrees (which is how they measure it for track days). Maximum reading was 95.1dB... so it looks like this system is no louder at high rpm, just MUCH louder than stock at low rpm.
I was getting concerned as I want to do UK track days and a trip to the Nurburgring (where they can be quite strict)