Why do you think Bi-Wiring improves the sound ?

No! Bi-wiring does NOT improve the sound if your speaker gauge is sufficient to the situation. As mentioned doubling the gauge of the wire “could” help... but maybe not. It is probably the least expensive “Audiophile” tweak you can try but do try and let the rest of us know it it actually works for you! I’m willing to bet it will make no difference in the actual sound. 
** actual results may vary :-)

Not a fan. 

Some years back I had speakers that could be bi-wired or bi- amped. 
    The only advantage I see now from bi- wiring is you will already own the wire if you decide to Bi-amp,Which I eventually did do.If that isn't a future consideration, don't bother. The money is better spent on upstream components, not wire or speaker mods. 

interesting take... https://www.qacoustics.co.uk/blog/2016/06/08/bi-wiring-speakers-exploration-benefits/

I have always bi-wired my speakers.
The concept makes perfect sense if you consider that the voicecoil is kinda like an electric motor.
Give it power and it goes.
but an electric motor is also an electric generator if the movement is caused by an exterior force.
The driver doesn't comes to rest instantaneously after being driven by the amplifier.
momentum keeps it going and that can cause the creation of current which feeds back to the tweeter. potentially.
Bi-wiring gives this current a place to go as it is drawn to the ground of the amplifier.
Path of least resistance and all that.