Hi pr0n,
I don’t know the exact specs for cat6 opposed to cat5, but we use cat5 for a digital video system, and once you extended off of the main source line more then 50’ it starts going downhill fast regardless of what you’re extending it with. It looks like your talking about 80 + feet total cable, so I would say it’s going to pretty tight since it didn’t work with the straight 80’. Do you have all the resources readily available to test it out first (maybe barrow from a friend), I would hate to see you buy it all and it doesn’t work, I would say save your money and go wireless. I don’t have an Xbox myself (PS3 man, but that a conversation for later
) however my friend has one, and has no problem with the wireless setup anywhere in his house upstairs, downstairs, basement, etc…