Replying to Boot flex question

I’m a quality skier, can handle any part of the mountain, but learning tricks at an older age is rough. I ski 120 flex boots, riding Armada JJ 2.0, and when I’m practicing 180s, working up to 360, my fucking legs are getting destroyed by my boots. I can ski double blacks all day and I don’t hurt like I do after a half dozen faceplants trying 180s. Shins and calves beat to hell, so much that I can barely ski the following day. Is my boot flex too stiff? What kind of boots and what range of boot flex are park riders working with?