I made the trap smaller, as objects had a hard time travelling up the first neck. Keep in mind a trap is used to keep bad odours and such away, so it doesn't need that much sway.
Maybe add a vertical shock absorber to keep the height of the water constant? i.e a vertical tube that expands when the undercarriage goes lower, and contracts when it goes higher.
this sucks.. Not only is it extremely poorly decorated, but it also has the most horrible track I've seen so far. The transitions between track pieces are edgy and make the cars glitch and collide.