after many years of reading shit i did'nt understand in this particular area of the forum, i still ended up just doing the standard SERT2 impulse purchase.
Hahaha. Ah well that's the way it goes. Dealer did all the work so can't comment too much, but can say VERY HAPPY with end result so thats the main thing eh.
thread here so I don't double up
http://hdforums.com.au/Default.aspx?tabid=71&forumid=15&postid=237395&view=topic
AND the chart below for your ref....