ok, I've been stuffing around with plugs for a little while now and have come up with some interesting results:
I've used
BKR6EYA (6 heat range copper)
BKR6EIX (6 heat range iridium tipped)
BKR7E - (7 heat range copper)
R5671A-8 (8 heat range copper)
ok, 6's are fairly ordinary. Iridium are a waste of money... No difference in performance.
7's are fairly ordinary too. No noticable difference.
8's.... I was able to add about 3-4 degrees into the 1\4 load to 3\4 load without detonation. However at full load, I was unable to add ignition advance without detonation issues.
But this gave the car a little more punch in the areas that had the advance, obviously, after being able to advance timing, and timing advance = power..
so yeah, just thought I'd share some more of my findings.
oh, and no starting issues. When the car is stone cold, it might need to be cranked over for about 1\4 longer than normal, but when hot... not a difference at all..