ORIGINAL: Jake Ruddy
As far as the 12" rule... has been a rule for quite some time and has nothing to do with the "old days" With 2.4 it is much less an issue.. FM / PCM it is worth listening to the people who design the products and following their guidelines. Sometimes it's not always possible to follow the 12 in rule.. but it is good to follow it if possible.
As far as the 6 volt thing on ignition, #1 There is no benefit to using 6v.
on a side note what is YMMV?
Your Mileage May Vary
Meaning if you do the same thing that I do, you may get different results, because EVERYTHING varies between setups, almost.
And - the "12 inch Rule" really has it's roots in poorly-shielded (or completely unshielded) *magneto* based ignitions from long-past days of yore.....about the same time someone conclude twisting servo leads and putting ferrite "beads" on them actually improved performance....
Kinda like the little plastic jugs of crap to put in your car engine that guarantees 10% mileage boost.....yep, YMMV....