OK, time for my 2 cents. First of all the splices create resistance, resistance causes voltage drop and there is Know getting around it. plugs are the worst. You need to know that amps is the driver for the voltage and thats what drives the servo. Wire size is important on long leads of 24" and longer because resistance is lower in a 18 ga. wire than it is in a 24ga. wire and you need it to push the voltage further and get there with more amps to use. So if your servo is wired with 22 ga. then extend it with 18 ga. and do it with one splice as close to servo as practical. Your better off buying the leads for many of the most common extensions or get the wire and ends and make them up. Twist splices are the best way to make the splice and no tinning is needed use rosin core solder when doing electrical work and heat shrink tubing over that, stagger the splices and then use heat shrink over the 3 splices, it will look good and your servo will like it. By the way many of the made up servo splice leads have gold pins, their the best.

Leroy