Interesting. I remember Brian from IMM posting the numbers he came up with and I'm pretty sure somebody asked him about the spark plug and he stated he did have a spark plug installed. I'm sure you probably know temp, humidity, atmospheric pressure, etc... all have an effect on the numbers. As well as what bench your using. I'll be interested in seeing what you come up with on the EQ's as I have a set I'm working over for a 408 I'm putting together (would already have it done if buddies would quit bugging me to do stuff for them, LOL).