Before doing the steps below, you may find it advantageous to remove all of the dark eco boxes from the race (if you destroy them they will not respawn when you enter the race again, so long as you stay on the same file and don't leave Precursor Basin).

Steps:

1.) Enter the race

2.) Go to the blue eco next to the pillar (this is the first blue eco that appears in the race)

3.) Collect the eco, and immediately afterwards hold brake on the zoomer (hold the X and square buttons simultaneously)

4.) While braking the entire time, go around the pillar, collecting the blue eco each time it respawns (braking ensures that you keep each eco)

5.) Do this until you have collected 6 total blue eco (including the first grab)

6.) Exit the race by going out of the entrance

7.) Go out a bit to give yourself some space to build speed, and then enter the race again (without braking)

8.) If done correctly, you will enter Dead Man's Gorge at maximum zoomer speed

9.) From here, you should be able to get otherwise impossible times on the course if you can manage to hold your eco until the finish line

Demonstration video: