[5.0 Pony]

i have found several complete units on ebay fot his price. Im not really sure about buying it from then though, but if its missing parts, that would mean I would HAVE to buy more parts, which is good for me, cuz then i would have anexcuse for spending more money. If and hopefully, when i get one, do i have to mess around with my fuel set-up? or my SD? can i still run my K$N Cold air? Also, the kits i have found come with a 6 # and an 8#, would it be better just to stay with the 6#? what would be the power diff? THANKS GUYS