If I am only wanting to put one sub in my 3, and have not aux outputs, is it better to wire it to the left or right channel?

 

You need to connect it to both channels.
Dual voice coils....

 

Optimally yes, you would want to connect it to both the left and right channels.

If you're not going to connect it to both, then it won't really matter which you use.

Obviously you'll have better sound quality and proper crossover if you get a new headunit or something and an amplifier and use proper AUX outputs that have a low-freq crossover/amplifier but to each his own.

And you don't have to use the DVC on subs, you just get better sound if you use both inputs.

 

put it on the right, there is more of an open spot for the wires and it looks better

 

Virgin is right AGAIN,,, you need both. hes the man..