This is true that it is not necessary, but still not a BAD idea. Especially because everyone around here ends up upgrading anyway. You know you will want to upgrade. I on the other hand have 1 alpine type r powered off of a audiopipe ap15001d at 4 ohms. I ran 4ga and am very happy. I may get some different subs in the near future, but it all good for now.
1600 watts RMS?????? This is the real question op. Based off your post I can only guess that rms is what you mean.
By the way, I am a huge fan of knu kable. Definitely worth it and it's not even that expensive.