I know this is discussed in many places with lots of different solutions
1) resistor / capacitor as per the instructions
2) APM, RC receiver, sonar, Xbee etc powered from a seperate 6A BEC
3) tightly twisted wires to reduce noise
4) mounted on the nose away from ESC's Xbees etc.
and i still have lots of big spikes and the climb rate is constantly noisy from this.
Have a look at the log file and you will see what i mean.