I recently installed Mark IV's on my 05 FLSTFSE. The "crossbar" which supports the Hwy pegs using a fat chrome-cross-bar runs right through the area of the spoiler. I had already changed out the stock buckshot floorboards for HD Flame floorboards. Had to change the floorboard support as well.
With that already behind me, the install only left the question: What to sacrifice the spoiler or the chrome cross support. According to tech support at Kuryakyn there is no solution: give up the spoiler. Now, even though the spoiler is chrome plastic, it still looked so great I wasn't willing to give it up. So, I didn't.
I cut away (fabricated, modified: whatever. If my brother Aussie can do stuff, so can I !!) and made the spoiler clip right on to the chrome-cross-bar. Took a minimum amount of time and I am thinkin' about having a real chrome spoiler made from this cut away model.
The Pictures are coming, give me a few to download.....