I seriously considered the EZwiring system, too. I ended up with the Painless chassis harness from
http://www.tristatemotorsports.com for $255. There's a ton of support at ffcobra.com for the Painless system and
http://www.my427sc.com has a ton of diagrams specific to the painless. I figured the wiring was going to be challenging enough without going at it alone.