Z5 is optically clear like Z2 Pro & I have found the same as you have with Z5. It does seem to look darker & a tad less reflective than Z2 Pro on my black paint. Z2 Pro really "pops" the flake in my paint........More so than Z5. I actually prefer the Z5/Z8 combo on black.
Z5 very much reminded me of the clear wet shine of EX-P. Both seem to slightly darken the paint, something I like on dark paint. Z8 over top added noticably wetness and slickness, FWIW.
