00b20vtecoupe

Hi, im running a fully built b20 vtec with 12.5 cr and im wondering what is recommmened for plugs. Im pretty sure when my motor was built my tuner used standard copper ngk's. I dont know if this is b/c the motor runs hotter and its better to use copper but i tried running iridium one time and it ran like ****. I believe i have coppers in it right now i dont know the exact number on them but they are the standard stock plug. please let me know whats recommended and what your running thanks.