well my gs-r that is fully built for street. was running like crap, lots of missing and back firing. so i checked the plugs, the shop that did the engine build had used some no name brand garbage plugs. now, im not sure if that is the reason for the condition of the plugs, or if it was due to a bit of a lean condition?? because the plugs were a bit white, but there was about a quarter inch of gap due to the electrode being worn right down. anyway, i installed the bosch platinum +4. im not a fan of bosch. btu they were only plugs i could find for my car in town. proly woulda been a week wait for some ngk's. BTW, the old plugs only had 15000kms on them.