When I did the big 3, I ran all new wire. There is no reason to run it parallel that I can think of. What size wire are you planning on using for the big3? I used all 1/0awg. I have used copper under the hood and have never had an issue with it. the reason to keep the stock wiring is that with both wires the total resistance will be less than either wire individually True, but we are talking a minimal value. I mean, a wire at .01ohms in parallel is .005ohms. Is that gonna make that much of a difference? And, no, I am not being a smart ass. 14v X .01 = 13.86v 14v X .005 = 13.93v Maybe it is an over oversimplification the subject? It'd make a difference on a meter. And why go about the extra work of removing the stock stuff when it actually helps?