Iíve just had the EDS remap done on my GSI . Chris has recommended dropping one heat range down to a cooler spark plug (also advised that double platinum are the best for a non turbo car but not convinced by that)

Iím currently running with Denso Iridiums IK20. The cooler plug is the IK 22. Iím interested to kown if anyone has dropped to a cooler plug and if so what the affects were?