I'm an NGK guy, been convinced over the years, I know everyone has there own stories anecdotes, etc. Anyway, I run NGK BPR6ES (Some places may refer to the stock number, 7131) standard resistor plug. Like the resistor for noise suppression in my radio. If you don't want resistor, BP6ES or 7333. Peter Arakelian - '71 TR6 - Daily Driver