ya. i have like 18g wire for inside that i want to either double up or make bigger. dose the rca guage matter to much? like that goes from the deck to the amp?
In my experience, the RCA size hasn't made a difference.... proper ground wire size (this often gets ignored) of the amp and good sized speaker wire can make a world of difference, especially if you buy one of those speaker wire/amp wiring kits.....
get a part time job and Best Buy so you can get the discount.... a $30 Rockford Fosgate speaker wire package can be had for $4.54 :D I forget what gauge, i'll look it up and post as an edit...
EDIT: I THINK 14 gauge would be fine..... I can't remember...