You can use the search feature here in the forum and find tons of advise as this has been discussed in detail. Probably the best advise I heard from anyone was to go to a bike show or festival and listen for yourself. Or even go to the dealer you bought the bike from while they are having one of their "events". Find that bike who's sound is exactly what you want and ask the owner what he has on it. Most people love to talk about their bikes.