Plug Wires, any advice?

The conductor thickness (or gauge) is what drives what would be best. Generally 9mm wires are good for most applications. Most of the Mustang sites sell good sets precut to fit. I'd be leary of paying extra for a "name" since they are all about the same in quality. And don't knock the auto parts stores products...some carry decent brands. Just make sure the package says Made in the USA. The last suggestion is just me.