Well, there's a couple of ways, besides messing with the OEM wires...
One is to go the show way, Bling Bling, and buy grossly oversized wires that attract those that like the looks and have been led to believe that enormous wires actually make a difference large enough to be heard, and the other way is to actually use something that's heavy enough guage to overcome any significant I2R losses without being so "pretty".
I've found Lamp cord to work well and be inexpensive. Plus it's handy as it's already a pair of wires.
But if you're looking for show, I'm sure there's lots of suggestions on the way! Where's that Welder's cable again... Yeah, 3/4 of inch diameter, that outta do it!
:blingblin
As far as connections, one of the least intrusive ways is to buy the connectors for the Bose at a Stereo shop. Unlike the SAT connector, the others are readily available. If you get both ends, one for the radio the other for the harness, you can "break out" the connections you want while retaining the others and not cutting into the OEM wiring.