Slipstream

 is an unlockable achievement for the Bloons TD game for the iPhone and iPod Touch. All Achievements are provided by an app called OpenFeint. You must have OpenFeint installed in order for any achievements to be available.

Info
This achievement is unlocked when you complete the Racing pack on Medium Difficulty or higher. It awards 15 points upon unlock. It is the silver achievement for the Racing pack, as indicated on the achievement's picture.

Related Achievements

 * Practice Lap
 * Bronze achievement - awarded for completing the pack on easy or higher.
 * Pole Position
 * Gold achievement - awarded for completing the pack on hard.

As indicated by the achievement names, if you complete the pack on Hard Difficulty, you will unlock this pack's bronze, silver, and gold achievements (if they have not been unlocked before). The same goes for completing the pack on Medium Difficulty; you will unlock the bronze and silver achievements.