The Fugu at Willow Springs really is an acquired taste. Pretty sure it is now my 'most failed laps' champion among TTs. I had never driven the track in reverse and only a handful of laps even in the other direction, and the car wasn't that familiar to me either (though with the engine swap had a couple of goes at Tokyo). My method is to challenge myself to find the rhythm on my own, just driving and experimenting. Usually I find gold time with that method within a few sessions (with road cars). Here, no way. I was something like a second away from gold after 3rd session. So I gave in and watched a couple of replays. Main technical error I was making was using the 2nd gear too much. The 3rd sounds and feels super sluggish, but you just have to stick to it. The gear change is slow and massively increases chance of losing grip. So use 2nd only to turn in, not for acceleration. Timing and smoothness is the way to go, even if this first appears like a drifting challenge.
That 1st/2nd turn combo is clearly the main culprit. Even with VR, where you -in principle- can see where you're supposed to go, it's very frustrating. You can't use any visual reference there, it's about muscle memory. Luckily it is the very beginning of the lap, so one can just concentrate on getting that right. As mentioned, 18.3 to 18.4 is a S1 worth going for.
Did something like 250 kilometers with this before finally a solid lap came together at 1:16.3. A real challenge, and not always enjoyable, but one of those TTs where I personally feel like I learned something.