Mario Kart Wii Guide - Mushroom Gorge - Mushroom Cup
1) Wheelie though point 1
2) Start a drift-boost here, then use that momentum to cut the corner at point 3 and start another drift-boost before the jump.
3) See 2
4) Your first Jump Mushroom. Land on it to hop across the gap.
5) Drift boost around the corner
6) Wheelie into the low road, cutting the corner with a drift boost. End the route with the boost pads at point 8.
7) this path looks faster as it's shorter, but it's not. Take the lower path at point 6.
8) See 6.
9) Drift boost around the bend and take the lower (right) row of mushrooms.
10) Upon landing, if you have a mushroom, you can cut the grass here and cut out the bend. Also, watch out for the goomba.
11) Start the next lap right with a wheelie.
Be careful when going over the jump mushrooms, as you can be thrown off course pretty easily, especially with the Wii Wheel.
Point 5: Left track
Point 9: Jump Mushroom Gorge