"Is there a wire that will make my Lsi15's sound like the Wilson MAXX??"
I don't think that there is a speaker cable that can do that. While there is no way to do all the scientific, double blind, etc. tests that some would demand (just the boredom alone would make it impossible) most of us ha made some effort to do some testing. And, I think, most of us agree that sometimes you can hear slight differences, most of the time no difference.
So, should you decide that you like the Polk sound but just want to improve upon them until they can compete with the Wilson MAXX, cables alone won't do it. You have to buy new power cords, interconnects, and speaker cable. They have to be expensive because only the expensive ones work, even though they are wire bought from bulk wire manufacturers, not some kind of new formula, and covered with dialectic material bought from bulk manufacturers, not some new formula. Then you must have hospital grade outlets (which only means they grab tighter so the plug can't easily be kicked out). You must go through a power conditioner not just a simple one to one isoloation transformer, which may be good enough for the extremely high tech industries but not for audio. Each solid state piece of equipment that doesn't reproduce sound through vibration unlike a Turntable, must be put on a vibration free stand that must be accompanied by a "scientific" white paper designed by someone who worked in NASA (all you have to do is a internet search, "Yup, there he is, says right here, janitor at NASA warehouse." And, that stand has to be very expensive or it won't work.
You do all three of those things then your Polk speakers will make your neighbors jaw drop, your wife who doesn't like music sit and listen or at least call out from three rooms away, and entitles you to make claims on how you were skeptical but, it made a big, no jaw dropping, no giant killing, no it was so much better you are going to keep the cables and buy even less expensive speakers because why throw your money away on expensive speakers or any expensive pre amp, cd player, tt, or amp.