I didn't gap the plugs in my '08 Matrix per the manual, and had an intermittent miss on wide-open throttle that was fixed by (wait for it) ... gapping the plugs, LOL! But since there isn't a specification, I just set it to 0.050" if I'm not mistaken (the gap was bigger on all 4 plugs out of the box). If someone can find it for the 1ZZ-FE and 2ZR-FE, it oughta be stickied.