Has anybody switched from stock spark plugs to the Bosch Platinum+4 (4 ground electrodes)? I'm curious if you noticed any performance difference. In my applications, I have not. If anything, I believe the performance is less. Perhaps this is due to the timing not being adjustable - or is it? It seems to be that if you use a more efficient plug, the timing could/should be modified to be less advanced, thereby increasing power. Otherwise, you might disrupt the timing curve and achieve poorer results overall. Thoughts?

 

Yes, it's a less efficient plug. No, you can't adjust them. Advancing timing INCREASES power and efficiency, not reduces. Timing is computer controlled on these modern cars anyway, so it's not normally adjustable.

I just use cheap platinum plugs, and reduce the gap more than spec a little for better efficiency. The spark fires a little faster, thus it advances timing, and I get better MPG. Increase the spark plug gap if you live in a country with lower octane fuel so it runs better.