I want to rewire my audio in a 1990 Accord 4 door (EX), what size gauge and how much
 

length do I need? Someone familiar with cars told me I should probably get about 25-30 feet of wire and look for 16-18 gauge. Does this sound right? If so, where is the best places to buy this for cheap online? I am guessing monoprice, but is there anything else? Thanks!

I moved this to the Audio section as I be KHA or someone else in here will be better at answering your question.

Might need to know what kind of "set up" you have and what all you want to re-wire?

Yep, need to know what exactly you are upgrading.

Assuming speakers, you want about 10 ft for each front speaker and about 15 ft for each rear speaker. Reason for the extra length is so that you can follow OEM routing and zip tie wires out of the way, taking a safer, more secure path requires more length.

18 awg is ok, 16 is better.

I like using CL2 rated in-wall speaker wire, a 100ft spool of 16/2 or 18/2 is pretty affordable.

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