ubec= ultimate battery eliminator circuit i belive it is

yes it regulates the voltage going to the servos, so when u do that u disable the one on the speedo ( aka the red or middle wire)

http://www.rc-monster.com/proddetail...=6vubec&cat=21


but no one so far has said u need one so idk, sounds good, thats what i would do also if i was doin a .5 still