| Could be your pickups are set too high, try lowering them a little.
If you've just changed from a normal core string to tapered core, the strings are now sitting with a lower action and also closer to the pickups and the magnetic poles of the pickups will be affecting the string vibrations.
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"you come into this world with nothing, you leave with nothing, so what have you lost?.....................NOTHING!" | 
SuperSteps is there a similar string? 
