I’m considering upgrading my speakers internal wiring

These are not old. Less than 2 years. I’m not concerned about the warranty as there really is not anything to a speaker other than drivers and crossovers… This is basic and not so much as an experimental experience. lol 

I changed the wiring and the crossovers at the same time.  Noticalbe and excellent changes, but can't say what the impact of the wire was.

Warranty law:  Something breaks, they have to show that what you did caused the problem to deny the claim.  Now if you're clueless and can't argue your side, you'll lose.  but if you can condfidently say that the wire you installed was as good or better and that it was installed properly, you haven't invalidated the warranty.

Now if you put an unapproved racing oil filter on your car and the engine blows, that's not gonna be good.  but if you work on the door handle and the windshield wiper quits working, no relationship.

Jerry

Go for it, I've been modifying crossovers and internal wiring for many years. One speaker manufacturer incorporated my mods in future production runs. Changing out internal wire, caps, resistors, inductors in crossovers usually results in easily heard differences. Determining exactly what you want to accomplish prior to mods important, research replacement parts to help ensure the replacements meet your needs. I also use the Duelund wire in my present speakers.

What the? This regular ol' speaker retails for ~18k??

Well, for what the dude charged you, he better already have put the best wire on earth, best crossover components. best of everything.