I have a Hitec 645MG metal geared servo, and a Hitec 7955TG titanium gear servo. I'm trying to decide which one I will use on my Slash 4x4. I know the 7955TG is overkill, but it has a much quicker transit time than my 645MG. I like quick steering. What can I say? My other concern is will I need an external BEC with the 7955? I will be using a Mamba Monster ESC by the way. Thanks.