I don't know about you but I don't wrap my servo leads around the mag coil. Since we are talking EMI here you would have to be very close to the source in order to interfere with the servo pulse that is in the order of 4.5 volts in amplitude.
As for RFI, since there is no spark gap in the primary circuit of the mag, the frequency is limited by the inductance and the capicitance in the circuit. It would be too low to get to the receiver.
The secondary of the ignition circuit is another matter. It contains the spark gap and is very high voltage. The spark gap converts the ignition pulse into a square wave. A square wave is defined as an infinite number of odd harmonics. Some of those odd harmonics will be in the range of the receivers RF and IF pass bands. The secondary circuit (spark plug) is the one that must be shielded.
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