Take the 2005 2.5RS. The manual calls for a 0.039" to 0.043" spark gap. The manual also specifies an NGK FR5AP-11. Now, there's a problem with that. The NGK FR5AP-11 is supposedly pre-gapped with the correct gap. However, NGK gaps the FR5AP-11 with an 0.044" spark gap! Considering that it starts out of spec and wear on the plug only makes it worse, this explains why all the spark plug manufacturers are recommending a different plug. It also explains why we've had to fix the gap on every set of "pre-gapped" plugs we've ever bought. NGK's recommendation, by the way, is for a plug pre-gapped to 0.041". This starts the plug out in the center of the tolerance and allows some room for it to burn wider over time.