I have heard that the Richard Grey High Tension Wires are neutral. I have been in the same boat, but have not tried them. The Bolder Nitro is very quick, dynamic and smooth, but I am not yet sure it is neutral. I am still trying to sort out what is doing what. I am not saying that they are not otherwise good, but these wires did not seem totally neutral in my system:
Cardas Cross
MIT Z Cord-II
Shunyata Snakebite