Spark Plugs NEVER LIE! We found 50hp on the Dyno by READING PLUGS? Jimmy Dale’s 434 is DONE!

We had a rough week at Bob’s but after 2 days of struggling with the new Dyno equipment, Jimmy’s 434 made less power than my 421 in the Malibu?
WHY??? Well, a quick plug reading told me all I needed to know.