Yeah, I don't like the St Croix one either, there are a lot of complex corners and turns you have to memorize and be good at in order to score a gold lap. A good first step would be to note what sector times the demo ghost clocks that way you'll know if you're on the right path. The part before the bridge is a trickster and needs caution while driving through it. Any wall hit leads to being disqualified from the race. I absolutely hate Sector 4 and 5. I failed many times in those sections, that's why I totally hate them with a passion.