I just installed the Pioneer DEH-P4800MP in my base roadster a couple weeks ago and got the same information from Crutchfield. I ended up calling their tech support people and asked why - if the wires come from the radio to the speaker, why can't I use the same wires?

He suggested that I might give it a try. I did just that - and it worked fine. The only other thing you have to do is switch the switch-operated power wire and the constant power wire on the harness. The directions they included in the kit were clear enough on just how to do that. From the time I removed the old radio until I was on the road listening to the radio was less than an hour - and I took it sl-o-o-o-w...

It looks really good in the dash, BTW...