You can go to far... correct, but too far is over .99V at idle, when you rotate the throttle plate with the voltage meter plugged in, you will notice that the voltage goes up, not down, so WOT is over 2V if I can remember correctly, not down to .475V... that's about half of what it should be at, at idle.
Piercing the wires will not do anything bad at all. Salt, water, whatever... I live in MI and have done this mod on over 15 different cars, and oldest being 6 years ago and still no problems, corosion or anything bad at all. You can't see the holes and you won't hurt a thing!
