Typically run a NGK V-power plug with 13-20 psi over the years with the 8 heat range. Is it time for a 9?
Part number R5671A-9 vs R5671A-8
Car was tuned on the 8 but have since gone to the 22-23 psi range from 20. Will it hurt or benefit me. Does the tune matter much here.
Car is about 800 fwhp, with 8.8:1 (?) CR and 22-23 psi 351.
Thanks
