do you think you whould get any more power or better gas milage from changing the spark plugs to a different kind?

 

The Bosch +4 is one of the worst choices* as we have seen the electrodes break off from detonation in Q45 and J30/G20 which have very very similiar combustion chamber shapes. The pieces scored the cylinder wall on 3 different engines I tore down.........no warranty when oem plugs are not used if the plugs cause damages.
* Doesn't even offer different temp ranges.........just a cheapo generic plug with lots of ad hype & dollars behind it.

NGK only in the correct temperature range for your application.

Spark plugs matter little because the coil on plug has tremendous reserve firing capacity as long as the gap is set correctly.

 

Q is right...I ran the denso iridiums and didnt see any gains...then ran stock when I went TT and then swapped back to the densos and noticed a gain...save your money until you hit 50k miles and swap them

Northface