I just upgraded my system with Sony AX7000 head unit plus Fosgate 2 x 6.5" front speakers & 2 x 6x9" saddlebags speakers. That'll will make your bike sound very clear and has decent bass. I totally recommend that setup. Sony AX7000 has built-in 400watt amp so you don't need additional amp, that is a great thing and less money.
A buddy of mine upgraded his CVO with J&M 6 x 6.5" speakers and 700watt amp, it's loud and clear but no bass and he is not happy about it after paying so much money for it. 6x9" speakers are a must for some bass, if you want more bass, 8" woofers in saddlebags (then you lose storage spaces) or tour pak. But like someone mentioned when you are out of parking lot or garage, more than 70% of clear/loud/bass are no longer heard, especially if you have aftermarket exhaust. I have heard some bikes with bigger amps flying down the road/freeway and I can hear the music but almost ZERO bass unless they have 10/12" woofer in their tour pak, even those with 8" woofers in saddlebags cannot produce decent bass flying down the freeway.
Do your homework and search for a system you will be happy with as you will sink some decent coins for the system. Like everything else, do it once and be done with.
Good luck and keep us posted on which system you decided to go with please!