With replaceable parts what are you implying? The only simple items that can be replaced on a brushed motor is the brushes and bearings.. anything else requires extensive work such as adding extra winds, cutting comm, changing magnets, etc. 15T motor should prove very essential to you for drifting, it provides a decent range of torque.. then again I only used a reedy and yokomo brushed motor for a long period of time. Reedy Flash motors are actually very similar to the yokomo brushed motors, they share the same design and offer tremendous torque from what I last remember but that was well over almost a year ago.