Q qwerty123 New Member May 18, 2007 5 0 0 Jun 17, 2007 #1 Jun 17, 2007 #1 What plugs should I use for a 150 shot and Holley Systemax heads? I have been told to use the NGK GR4's but I am not sure if those plugs are 2 steps colder than stock. What do you guys think?
What plugs should I use for a 150 shot and Holley Systemax heads? I have been told to use the NGK GR4's but I am not sure if those plugs are 2 steps colder than stock. What do you guys think?