Do you have a spacer on top of the front J springs? Or are the rear Slee's mediums? Not as much stink bug as I would expect with your set up. I ask because I have a small collection of springs and your combo is one I have contemplated trying out.
I have 1" spacer on the J's up front and ALSO had to put 1" spacers on the Slee 4" mediums.
I had posted earlier, but the Slee 4" mediums feel much better than the 864's I had in prior. The standing free height of the 864's vs Slee 4" were almost identical, however the Slee had slightly thicker wire diameter and an extra 1.5 wraps of coil. I'm very happy with them. I feel that the 863J's were too soft and 864's were too stiff.