I will never understand people who do illegal things over their own IP. Is it really that hard to find an open access point? Way back in the day when I torrented all my content I used a long-range wifi antenna connected to a public AP and a dedicated PC with a scrubbed drive that never connected to my home network.
The long-range wifi antenna has always sounded like an opsec urban legend to me. You'll be able to transmit signals to the router, but can you really receive them with any sufficient fidelity if the router itself does not also have a long range antenna or unusually high transmission power?
A 10dbi gain yagi boosts your transmitted and received signal equally.