Lets say you are messn with the fuel and spark curves...how do you know where and when and how much to change it by? How can you tell you need some more spark or fuel up top or around 3400 rpms? This is the only part that confuses me on the whole PROM burning, i get everything eles.

 

You use a scantool or Craig Moates' software + laptop, looking for spark knock and/or BLM readings out of spec. At WOT you look at the O2 sensor, want it in the 920-980mV range according to my notes.

If you're seeing spark knock, you reduce advance in the table accordingly, etc.