I got a set of 30thou oversize a15 pistons from Master Parts in Cape Town.I use a 290 degree cam in at the moment.What setup are you running?

The gap entirely depends on your ignition system. Doesn't matter if it is 12.5:1 or stock 9:1 compression.

If you have stock points ignition, set the gap to the high side of the stock setting (0.035 inch).

If you have Nissan electronic ignition, set it to that specification (probably 0.035 inch, but possibly 0.042 inch for newer kinds)

If you have MSD multi-spark CDI ignition, use the MSD recommendation.

In general, larger gaps are better but only if the ignition system can handle it.

I am running BP7's at .75 to .8mm with a MSD blaster SS coil, no problem

What pistons did you use in your A15?

Using a big VDL cam I presume?

I was wondering if anyone can tell me , in my A15 with a compretion ratio of 12.5:1 what would the guys that know make spark plug gaps