Hey, there's a forum. I had no idea. Fast acceleration just needs a lot of practice to get right and I miss it more than I get it. It's all just a matter of timing. As per your question, you switch back to high immediately. Tap tap. If you get it, you'll see your RPMs spike and then immediately drop. The best way to know you got it is that you'll be hitting 200 km/h as you hit the first round of bleachers after the first line of palm trees end. Check that run that takojaki posted. If you're hitting 175, you got what I call a half-assed boost start. Quit and try again. It's always 200 right there if you got it right.

As for the Devil's Canyon 54, a 55 is what you should get if you do everything perfectly, but don't nail that last blind to the left before the rocky corridor. If you turn perfectly going in there and never drop speed, you can barely squeak a 54 out of it.

If you have any YouTube/Twitch footage of your runs with the issue, just let me know and I'll help you any way I can.