Running too large of a gap with nitrous will not "foul" the plug... the increased cylinder pressure from, say, a 150hp shot like mentioned, will 'blow-out' the spark causing a miss, or in other words, a backfire. If you get lucky, you may get by with just a damaged air filter, or worse, a blown head gasket combined with damaged induction components (MAF meter, split inlet pipe, bent TB blade, grenaded intake, etc.)
I wouldn't suggest running any more than .035 w/ a 150hp shot, even with a 'hot' ignition system. That is how I would approach the situation... and do
