I own a brand new American Models hi-rail Pennsylvania K4 Pacific loco and tender that was upgraded for DCC operation, as well as six American Models Budd passenger cars [all of which are relatively heavy]. Set control is via a Digitrax Zephyr DCS50 system. The max possible consist speed- -even hauling only three [3] of these cars- -is quite slow around my small loop of Lionel AF FasTrack. What electrical component upgrade must I make so that my loco can pull all six of these cars at a reasonably fast speed?