I can't say for sure about AMP, as far as their kits go, but I've heard a ton of bad press about them, as far as their customer service/people skills go. They're rude and unfriendly as all heck. Being that I live near their actual location, I stopped by once because I was looking for their used Mustang parts branch (All Mustangs); the front desk guys there were kinda snotty about answering my simple "where the heck is the other place?" question, but the guy at All Mustangs was cool as heck.
Just something to consider, I guess. Sometimes it ain't what they sell but HOW they do it that makes the difference for some folks, y'know?