Hello Stephen
I used your technique ( mini ramp to jump) at the early beginning when i discovered how Cheng was about when reversed. Cheng forward got that mini ramp after the open section but with no real benefit using it.
Anyway, back on the black one : when i saw MadIce & AH Quadzilla beating my lap time by far i tried to understand it but Matthijs gave me the solution : turboing & shortcutting : i tried several location where to turbo the best .
Before that you need to have in mind to really up your nose as much as you can while turning right and doing a BR which is not an easy task to link those 3 actions in a milisecond
If you turbo immediately after the end of the magstrip when you are on the right side of the track you ll get a respawn ( try to test where exactly the respawn is cause when you found the limit it will be at that point to throw the turbo)
My lines are : get that speed pad on the left, stay left till the mag strip is finished then after you found where exactly is the 'respawn limit' you turn right & up your nose , throw your turbo , BR, and point your ship to the direction of that building ( which is on the right side of the track before the robot builds robots billboard : if you got that good diagonal line in the air you can land smoothly on that right part of the track where the left long curve is almost finished ( if you are too far on your right you ll hit the building side) if you throw your turbo too late : you ll have too much speed carried and hit the R. builds R. wall ( plus you not really shortcut in that way : you almost do that low ramp technique we were using before).
When everything is doing perfectly you can 'go out' from that left curve by a sweet turbo boost induced by BR hit those 2 speed pads on the left before the open section and entering the looooong right curve and maybe if you lucky get a new BR while turning that long right ( don't hit the walls before doing it and try to land on/ or / near that unique speed pad in the middle of that curve )

Last tip : the more you avoid airbrakes ( except sideshifts) the speedier it is ( i know it sounds logical to many of us here but for me i had to relearnt few things about the way i am controlling my ship compare to older wipeouts) multiple slight tap on dpad left or right is always better than 'compensating' with airbrake left or right

Thx SL again for that 2097/XL Hud where the speedometer is displayed enoughly big to let me watch it constantly

21.81 / 1.53.48 my latest score about Cheng reverse