I have a Frontier ('02 CC LB 4x4). I haven't installed my Empeg yet, so I can't give any suggestions. I keep trolling this board hoping that someone else posts some suggestions for me.

There's a Nissan Frontier forum on the net that has a section devoted to audio. They have wiring loom info there, too. That's actually where I first heard about the Empeg, actually.

I'll probably tear out the original HU. It's okay, and definately better than most stock systems, but there seems little point in keeping it in there one I toss in the Empeg and PCA's tuner kit.