Heading into the 2018 Houston SX, Red Bull / KTM’s Marvin Musquin had a full head of steam. The Frenchman came from behind the win the A1 opener and looked poised to make a genuine run at his first-ever 450SX title. In the sport of SX, though, things can change quickly and in Marvin’s heat race his season went sideways real fast through the whoop section. The #25 went down through the whoop section and…