Hello Matt,
Boosted is a type of program that speeds up the motor. Most of the speedos have this feature. if you are coming back to racing maybe start off without boost until you get used to the track.
The following motor and speedo are a good value option. The Speedo also uses Hobbywing software so its easy to program for boosted & turbo functions.
You can get plenty of help from the guys at the club re set up etc.
http://www.hobbyking.co.uk/hobbyking...arehouse_.html
http://www.hobbyking.co.uk/hobbyking...arehouse_.html
Hobbyking also have good Lipo and charger options.
All the best
Paul