Ok so the manual says to change the spark plugs at 100k miles. Well, better late than never, right? I am very eager to see if this makes any difference in MPG or performance. Installation was very easy and took only 45 minutes including prep and clean up, thanks to this informative video which I followed closely: https://youtu.be/1gcbt1KfcRs
I installed a set of Bosch double iridium plugs from AutoZone. Total cost was $30.55 and includes a $10 AutoZone gift card rebate.
The Bosch iridium plugs have the gap pre-set to 0.044". This is slightly smaller than the spark gap recommended on page 292 of the owners manual of 0.049–0.053 inch (1.25–1.35mm), however there is a note on the Bosch box: "Do not gap, Do not use anti-seize". Tightening torque is also listed on the box as 20Nm or 15 ft/lb.
Here are some photos of the original spark plugs (after 140k miles):
