The first drop, and the mid-course backflip, are the two obvious ones.
There are two elements near the end (right before and right after the 2nd raven turn) where the train AND the seats flip over simultaneously... but since I've only ridden it twice I don't know if your head ever points at the ground there. It's disorienting as hell and a lot of fun tho... :)
You know, that's a wierd one. When you are ridding it, you have no idea which way the sky is or which way the ground is, MADD GOOD!!!!! You really can't list a specified number of inversions unless you only count the spinnig seat flips. All I really clearly remember from that ride is the view of the first drop from the front seat: A very unique way of facing the rider off the crest of the hill, MADD GOOD, MADD GOOD!
Structurally inverting wise, X performs it 4 times. The amount of times riders actually experience the "head-over-heels" sensation is 2. Riders do not go upside-down on the half-twists. That's a misconception. They are peculiar and strange maneuvers on the 4D coaster. Riders are just quickly twisted from a forward riding direction to a backward one, in one smooth spin. The Raven turns basically invert the track from a suspended coaster to a conventional "riding on top" coaster, vice versa.
Hmmm... sorry, but I gott go with the Moosh on this one. You do go head over heals four times total on the coaster. Now, the TRACK itself actually only goes "inverted" twice, and when I was asking Duane this question he replied that since there is "dispute" about actual inversions that he would only count the number of times the track itself gets inverted.
But Moosh is right, you are "upside down" as in your heals are over your head in a line perpendicular to the ground at the bottom of the first drop, during the mid course flip, during the first half twist and during the last one up to the brakes. But, oddly enough, not on either raven turn.
/\ I'll REPEAT myself again, YOU DO NOT GO UPSIDE DOWN ON THE HALF-TWISTS. Riders experience the "upside-down" sensation TWICE during the ride. 1) First drop; 2) mid-course flip. The track-riding position switches back and forth from "inverted" to "sit-down" FOUR times. 1) First raven turn; 2) First half-flip; 3) Second raven turn; 4) Final half-flip