Speaker wire size

[Just 6T9 CHGR]

In general, will the thickness of an aftermarket speaker wire affect sound quality?

I am running some Pioneer 6X9's in the Charger for the rear from a 40 watt head unit.    I am running some really thin (16-18) gauge speaker wire.   For some reason the sound output from these speakers doesnt sound like it should.
The polarity of the wires is correct.  Would thicker speaker wire help any?
Thanks
Chris

[8WHEELER]

Hey Chris size does matter  sorry I had to. I have run larger than the required size of speaker wire
most all of the time, with great results. Having said that I have run the small wire a couple of time and
the system sounded OK. But I am not an expert in speakers or stereo's, so I will let the experts chime in.
But I do run a 60 watt high power stereo in my red car, with four 6x9's with the thick house size speaker
wire and it sounds great.

Dan

[Just 6T9 CHGR]

Thanks Dan.   Since I have my rear seat out now for recovering, I might just go ahead and replace the wires.......

[Nacho-RT74]

16/18 wires are really enough to drive 40Ws. I'm a profesional sound tech and we run 12 gauge wires to 800W speakers systems what is A LOT more than that.

But is true that heaviest is better, specially along the distance.

Anyway, check if 40Ws are RMS kind or PMPO kind. Most of time they are RMS what is an average output. But if you check factory Stereos outputs wires you will notice that speakers outputs are THINNER than 18 gauge in fact and drive the output power.