xx / 10.64 / 10.64 you need to be more daring with regards to how much of a gap you jump over to the bridge, instead of hugging near the arrow sign (which isn't the greatest line).
xx / 21:82 / 21:91 - Hitting the turbo pad is slower, since you move away from the centre line, stay on the inside.
You should be putting your uphill projectiles (one or two bounces) in sooner, instead of at the top of the hill, it should be almost immediately after the first turbo pad. Contrary to the speedometer, the turbo pad does not speed you up.
27:57 / 25:61 / xx - moving too far away from the centre line
For the start of each lap, instead of jumping off the first drop-hill, you should try cresting. Preferably from the middle. On laps 2 and 3, this will equate to a week form of Speed Ghost with a few froggy hops will stretch out.
For the first lap (this line takes some practice), its possible to do a mid-air-powerslide->into/or normal powerslide, which crests the first hill, then performing 3 successive boosts, reaching Yellow fire sooner.