Ok, so, I'm about to pull the trigger on a few upgrades I've been eyeing for awhile. One of them is American Racing Headers for my 5.7 auto. I went to order them from LMPerformance.com and they are asking me if I want Ext Harnesses. My questions are, is this a good site to order from and what are these harnesses they mention and do I need them? Also, does anyone have the ARH for a 5.7?