I make a habit of placing the throttle servo, ignition, ignition battery, and ignition within about a 6" circle. Typically the throttle servo, engine and ignition are within 3" of each other. The battery will always go where balance requires it. However, I use only quality parts that have never been crashed and proven to be functioning correctly, secure all the connections, no metal to metal contacts, and assure the spark plug lead is correctly secured to the spark plug and does not rub on any other component, including the cowl.