1985 Trans Am with a gen 1 small block 350. Car is running great but have been thinking about doing a plug swap. Have heard people rant and rave about e3 plugs. I'm also considering iridium spark plugs. I run ngk iridium plugs in my bike. My question is the results worth the extra money?

 

Worth the extra money? No. Standard copper plugs will fire just as good but they don't last as long as a platinum plug. Plugs that are difficult to replace should be upgraded to platinum just for that reason. If you're willing to replace plugs every few years then copper plugs will just just fine.

If you did a back to back dyno run with new copper plugs then new platinum plugs, there won't be a change in performance results.