Well i run on a standard Z20LET map and after running the NGK iridiums for 2 years i decided to try the Bosch super 4 spark plugs.
So tonight as i started to take the old plugs out i was shocked to find that i could loosen them by hand as all 4 of them were loose.
Number 1 and 4 threads were covered in oil aswell so might of been loosing some compression who knows.
Still the engine seems to been running good as they all were a light grey white colour which i believe is a good sign.
Put the new bosch ones in with a torque of 25 NM and put everything back together and took her for a run and i must say ive covered 50 miles and im very impressed with the super 4's so far.
Maybe i was not getting the full benefit of the iridiums with them being loose but my car seems to be that bit more responsive in 3rd and 4th gear