There has been an on going war about bosch vs ngk factory plugs on the SR20 for ages. I have no probs running bosch plugs in my car unless I drive it hard and it's extremely hot outside it begins to idle very rough and lose power and even sometimes feel like it's misfiring while idling or accelerating. Only thing I could come up with from personal evaluation is that Bosch plugs run considerably hotter than the stock NGK's and end up preigniting the mix in the cylinder. I went back to factory NGK's (after I sold my first born and my soul to Nissan) and the problem went away. The factory plugs are way overpriced but after you make that switch you'll see why it's worth it.