Used to run Denso IK27's in my sapph, best running IK31's tho, as after extensive testing, the 31's stand upto a lot more abuse over time and are less likely to succum to core or nose damage

As for gapping them, I never did, they came pre-gapped at 0.8mm and thats how they ran in my car (using the MSD Coilpack system aswell).

However, if you find you need to gap them, then there is a special way to do it, as the irridium nose tip is very brittle and may become damaged if gapped wrong.