ive just rembered that when i got the car, gave it a full service. took out the plugs and found the wrong type were in it. the type that were in it are generally used for the avensis and corolla. the ones i put it were genuine Toyota iridium tipped, p/n: 90919-01178 (denso pk20r11)
After changing these i noticed a slight difference in low end torque, as expected.
so if yez have a spare 10mins, id advise to check.
its worth it