mine aint in the car yet. you may still beat me lol.
1000+hp hondas are running ngk 8 heat range. you are right, 9 is too cold. 6 should be fine.
I was looking for iridium plugs for my 2.5L jeep wrangler and they have a crazy extended electrode and insulator and i couldnt find a ngk iridium equivalent. had to go with an autolite xp iridium. we'll see if that adds some mileage or any performance as it is a dog lol. needs boost.
Brian