No regulator is required unless you run Lithium batteries. 2700Mah is perfect!
It is always a good idea to use HD extentions on anything over 6", especially with high torque servos.
NOTE: Please do not post in this forum unless you are a Hitec rep or have a question as per the guidlines posted here:
http://www.rcuniverse.com/forum/m_2603615/tm.htm
Mike.