when i did my engine swap 2yrs ago i put in boshc +4's cause i thought they would work alot better. well i thought i noticed a difference but wasn't sure since i haven't driven the car in so long. for a while i've notice a very very slight rough idle but i thought it was all in my head...apparently it was not. i did the acis mod and p&p my intake plenum and manifold i also removed all the grime that was in the top end of my motor. the rough idle was going away but i still couldn't figure out why it was acting this way. so i figured i since i'm changing the oil i might as well change the plugs also. i removed the +4's and i noticed that they looked like they were working too hard to make a spark so i compared them to normal platinums and i noticed the electrode was further away on the +4's then they were on the normal platinum plug. so i guessed this must have been my problem. when i changed the plugs i emidiately noticed a big difference. the car responded very well and had better pick up at passing speeds.
so to make a long story short...don't buy +4's or +2's just normal style plugs work the best all those gimic plugs hurt your performance.
so to make a long story short...don't buy +4's or +2's just normal style plugs work the best all those gimic plugs hurt your performance.