I have the Karma Rca and speaker wire, and they are thick. I had a hell of a time getting the speaker wire in the doors. After struggling with the first run, I decided to run the Kord blue instead of trying to squeeze another karma cable in the doors.
If I have to do it again, I'll go with speed wire or something similar.
Or this, I have a roll of the 22awg, and they're flexible enough and easy to work with. Amazon.com: GS Power 16 Gauge Wire (16 AWG) - 100 Foot, Pure Copper, Stranded Electrical Wiring for Speaker, Automotive, Trailer, Stereo and Home Theater Applications - Red/Black : Automotive