How much money are you willing to spend to get lower? I have a new SERGU and had to put Legend Air rear shocks on it...drops the rear 3 + inches when I need to. But, they ain't cheap. I've got a 29" inseam though, and I think I'm shrinking as I get older. You can also adjust them "on the fly" for different road conditions with a push button controller mounted on the handlebar.
Personally, I would not waste a dime on any suspension components HD offers. IMO, it's blowing money up a wild hog's butt.
If you want a 1 inch lower, high performance, FULLY adjustable (three ways) shock, which will give you the best ride you've ever had when properly set up...get a set of 300mm Bitubo shocks from Dan at Traxxion Dynamics in Woodstock, GA. But, good chit is never cheap...or, you can probably get them from Jim (HDdude) here on the site. I think he is a Bitubo dealer...I know he's a Traxxion products dealer, so am making that assumption on the Bitubo shocks. They are made in Italy, and have preload, rebound damping, and compression damping adjustment.
Some here are running Works shocks, with good reports on their top of the line product, but I cannot attest to them personally.