On both turns, you can make a tighter, faster turn by using a mushroom and drifting on the grass. The second one is pretty important in Lap 3, so get a power item if possible.
Strategies
Excitebike Arena is primarily a running track, but it can get very chaotic at the final stretch, so stay defensive there.
Shocks are super powerful in a Lap 3 situation due to only you having the speed to go through the ramps and the final shortcut.
Due to being shaped like a stadium, Bob-ombs can only be useful to trap falls from ramps and the turns.