which one is the best to get for my is300... for best balance of performance, mpg, and longevity?

my main concern is the life of the plug/gas efficiency, that is why im trying to find out what the main difference from the denso's .4mm gap to ngk's .6mm gap...

- thanks!

 

Honestly, Iridium is Iridium.. you cant really go wrong with either of those plugs. I highly doubt you will notice any difference between them.

 

I've used both in the past. I couldn't tell a difference between the NGK & the Denso, and the NGK's are usually much much cheaper so that's whats in my cars now.

 

I have also tried both, that's going back awhile and also couldn't sense much of a significant difference. I ended up going with Torquemasters, which really seemed to do the deal on that Mexican gas I was running for so many years.