Mario Kart: Double Dash!! Tips

Secret Passage
ON Yoshi's race track after you go under the tunnels or bridges or whatever....boost off the edge as if you were going into the water but there is a tunnel. You may have to try a few times to boost in the tunnel its a tuff one.
Also, in the raceway where you go across the bridge and there are those boosters on each side. well on that raceway right affter the finish line there is a path to your direct (sharp) right that goes down to a pipe which boosts you out and ahead.