I've been doing a lot of research on this also. I have decided to go with Biketronics RG 14 and up kit. I spoke with Bill at Biketronics just yesterday about my plans and this is what he told me. The RG 14 and up kit includes the 2180.14 amp, titan 6.5 speakers, and all hardware. I am planning on putting the rear speaker pods on mine (added the tour pack when I bought the bike). He told me they are recommending the Alpine SPR60 speakers for the rear. All four will hook up to the 2180.14 amp with no problem. With this set-up, you will lose front/rear fader control. But if you want to upgrade to the 4180 amp, (another $100), it will permit you to have fader controls.
If you search this forum, you will also find various discount codes. I mentioned that I was planning on using the RGintro code, and he confirmed this would take $100 off. So it actually washes out with the amp upgrade.
I have spent several weeks creeping around this site for information, and will pulling the trigger on the Biketronics system real soon.
Just my 2 cents….