Can anyone help me out here?  I've tried using several shroom strategies but I don't really like any of them.  What do you think is the best shroomspot/shroom strategy for Mushroom City?  Also, does anyone have a really good flap shrooming strategy?

For my 3lap I used 2 mushrooms on the little path on lap 3.
For flap I use one before the big round corner (the corner before the straight piece of road before the final stretch), and the other to the left of that rectangular hole in the road at the end (there's a truck there on lap 2, so i go between the hole and the truck).