Can someone please tell me why there is a difference in this chart from NGK spark plug ref page Re: BKR5EIX-11 plug
NOTE on my photo the 3rd and 4th line from the bottom of page see the difference in HP
both 1998 both4.0 Ltr 363hp & 284hp
so what makes the difference between these motors?

 

Supercharged and naturally aspirated.

 

4 words that deflated me, thought I was gonna get lucky with more hp somehow LOL
thank you again I guessed there would be the SC at the end of XJ.
Ta Cambo
love the supercharged cat heee