View the latest statistics on motorcycle accidents, as well as Australians perceptions of motorcycle safety in Budget Direct’s latest survey.
Start there then follow the citations to the Aust Bureau of Statistics. The initial link a an insurance company meta-analysis and given their business is risk assessment they are usually the best informed research data publishers.
28 riders were killed in WA and at least 5 were harley riders representing around 18% of total fatalities which is greater than their market share percentage. So it's a safe conclusion to draw that you are really no more or less likely to be in an accident on a loud bike (the only assumption here is that all the Harley's were loud)
I don't doubt that in your case being louder MIGHT have got you noticed and I also don't doubt that more appropriate lane positioning (is not sitting right beside any vehicle for 150metres) would DEFINITELY have