your ISP can (and sometimes will) get pissed about torrenting copyrighted stuff. comcast will get mad over it for sure and threaten to cut your service if you continue. you can use VPNs, but any US based vpn (good speeds) will rat you out if/when questioned about your traffic.
friend of mine has a server in China that he torrents stuff to, then SFTPs it to his home rig so no one can see what hes transferring.