dennday67 Well-Known Member Joined Feb 6, 2010 Messages 730 Reaction score 31 Location Yakima, WA May 21, 2011 #1 Will I see a difference switching to the ZFR5N from the ngk GR4 with my new HEI ing?
EL5DEMON340 Well-Known Member Joined Feb 6, 2009 Messages 4,199 Reaction score 504 Location Aurora,IL May 21, 2011 #2 as long as your spark is jumping the gap fine with the old plug i don't think so