you need a conversion kit so that it works from the bikes controls and volume increases with speed .On my 06 FLHT I used a Biketronics kit and Sony radio CD player, it's simple to fit and considerably cheaper than the Harley unit.
+1 for Biketronics - just did an install of their retro radio kit for a buddy, I'm no electronics expert - but the kit was easy to wire up, the customer service was great when I had a question on the power wire and the performance of the Sony headunit , the 80 watt speakers and the ipod compatability is great.
I used the Biketronics kit on my '07 FLHT and it works great. I also have the Hog Tunes speakers and I added the Polk Audio DB1000 Tweeters. I have had it for over a year now with no problems. I highly recommend it.
imo infinities are better than either jm or hogtunes. if you are running an amp then i reccommend jl audio or mb quarts
I am running the stock unit with no modifications.
Sorry, but i dont know what imo is, i guess it is a different speakers brand, isnt it? i am from Europe, so excuse me.