After going to several parts stores asking for spark plugs that were 1 or 2 heat ranges colder and not platinum tipped for 96 vortec heads I had no luck. Finally, I went to Napa and pretty much right off the bat a girl working there knew exactacly which plug I needed. Keep in mind that the threads on the R45TS plug aren't long enough. The right plugs with the correct length threads is the R45LTS. They make a R44LTS and a R42LTS but not a R43 or atleast that is what the lady said at Napa. I will be using less than a 150 shot and will be using the R42LTS. This plug is 3 heat ranges cooler and I was wondering if it is too cold a plug for my intended use?? What about for just driving on the street off the bottle?? Should I go with the R44LTS instead? I was trying to play it safe by buying 3 heat ranges colder.