I have heard from several people that the Bosch +4 are just as bad, if not worse than the regular Bosch Platinums. Here is a pic of my old Bosch Platinums:
Notice the one on the left has a small hole in the center of it. The one on the right is filled in. I don't know which one is normal, but I will never use them again. When I switched to Bosch, I definately noticed a loss in power.
By looking at the picture that you posted of the +4, it looks like the center of the plug is the same design as the regular ones. I would just stick with NGK's.
The one on the right is normal the one on the left is very abnormal I hope the platinum tip didnt fall in to your engine and scratch your cylinder wall hopefully it just eroded or went out the exhuast valve.
i had those in my car! till one worked it's way loose and shot out of the hole! screw bosch! if it weren't for the little plastic sparkplug cover(which, btw, was cracked completely in half) the lil fcker would've gone right through my hood.
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