First from an engineering perspective, you cannot produce more horsepower based on wires - so any claim to this is BS.
Second if you have an EFI bike, use only the stock or SE Delphi specific wires exactly Hippo says. Here is why.
Although most aftermarket ignition wires will perform the function of conducting coil output to the spark plug, what is important to HD EFI bikes is EMI suppression and resistance. All electronic devices can be effected by EMI emitted from ignition wires, and the problem is often exacerbated by installing a high-output ignition system so don't do that either. As the bike ages, engine management sensors and wiring deteriorate and become more susceptible to EMI radiating from improperly suppressed ignition wires. HD EFI tuners should also take into account that the ECM uses resistance in ignition wires to sense detonation (ionization across the gap detected by resistance) and then kick in spark retard on the appropriate cylinder.
If you put in "low resistance' wires and take this away, then you WON'Tt get knock retard and you WILL get detonation that would normally be eliminated. DTC codes as da Hippo says will then be set -probably 13XX codes for ignition voltage/coil problems.