I would agree that an aftermarket system is an improvement although the cost/benefit analysis is a matter of opinion while your bike is moving. If Canada is a helmet country, pretty sure it is, you may want to invest in a set of J&M headsets. While the Harley headsets are okay the J&M's are the way to go if you wear a 3/4 or full face lid. That is one upgrade where you will be able to recognize a difference when you are rolling down the highway since it places the speakers inside your helmet and a good helmet will reduce the ambient noise. If you wear a helmet that covers your ears you have cut down on your ability to hear many of the frequencies that would be improved by an aftermarket system of speakers and amps, rather like wearing ear plugs. If you talk to a knowledgeable audio engineer or an otolaryngologist you will find out that without a helmet, the background wind noise interference, and with a helmet the padding and insulation have markedly reduced your ability to hear specific frequencies ranges. These forums have helped me many times with decisions because you will get many opinions and differing viewpoints so in closing I will just say best of luck with whatever you decide.
