The old JC Whitney CD unit on my D200 finally failed so I upgraded the whole spark path which essentially had not been touched in years. New Mallory HyFyre 6a CDI, new Mallory Promaster coil, Magnecor 8.5mm wires, new Bosch cap and rotor. At one point I called Mallory tech support to ask a question and in the course of our conversation he told me to be sure to use non-resistor spark plugs, which I thought after we hung up, why? So a couple of days later I was on Mallory's web site and i submitted the question as to which type of plug to use with this set-up using their web site tech support form. The answer comes back...resistor. So I'm like, do I ask again and go with the answer I get 2 out of 3? Heck no, let me come here and ask the masters. Is their some rule about resistor vs non when it comes to CDI?