Did you use spades with your Furutech outlets?

[Energy]

As those have said above, a heavily crimped spade would be better than bare wire. If bare, solid core would be best. However be careful of the receptacles that have the screw placed in-between two wire holes as the screwing down process would be slanted and not make a good connection with the wire. For this purpose it would be better to either directly solder the wire to the contact area or create a fish hook shape out of the bare wire to tunnel it down before pulling up for an even clamping pressure. Otherwise go with the spade method for simplicity. If you want more assurance, flux and solder after crimping onto the spade.