Best way to wire my door speakers?

[1meanZ]

I'm installing Infinity Kappa 6.5 in. componets in my doors of my F-150 reg cab. Can I tie into the speaker wire behind the HU or should I just run new wire from the amp through the doors to the speakers? It seems like a PITA to run the wire through the doors. Will 18 gauge suffice for the componets? I'm using 12 gauge for the subs.

[HLLRZR13]

always run new hot leads even though its a pain is the ***. But you should always use 18 or 20 gauge speaker wire for tweeters and 12 to 16 gauge for component woofers. Because low frequencies travel around the outside of the wire so bigger wire means better bass response. And high frequencies travel straight down the middle so smaller wire means less low frequencis can be reproduced so cleaner highs.