Which Spark Plugs?! Denso SC20HR11, SC16HR11, or IXEH20TT??

I believe IXEH20TT is the updatef sparkplugs design that the 4th gen Prius use and actually compatible too.

I probably will use IXEH20TT from the fact it is Iridium with platinum ground and still have similar lifespan 120k miles. It makes sense and actually better and cheaper because it has smaller iridium tip.

 

Seems to me that Denso is promoting the IXEH20TT for "performance" and the SC16HR11 for longer life.

 

That's generally the tradeoff; the performance upgrade plug, if the stock plug with its wider electrode is having difficulty igniting your mixture, or otherwise use the SC plug made for OE, as the wider electrode will last longer.

You can look at a number the car's ECM computes for you, called the misfire margin, to find out if there's any reason to think your current plugs are having any difficulty igniting your mixture.