ik22 are colder heat range plugs than ik20 ..
taken from denso site:
The ability of a plug to dissipate heat from the combustion chamber to the cylinder head.
The heat range of a spark plug primarily depends on the length of the insulator nose.
Choosing the correct heat range is very important. Standard vehicles should use the heat range specified by the manufacturer. If your vehicle is not set to standard specifications you may need to change to a spark plug with a different heat range.
Spark Plug temperatures must remain between
450°C-900°C. Cooler temperatures won’t allow the plug to ‘self-clean’ by burning off carbon or oil deposits. This will lead to misfiring and poor acceleration. Hotter temperatures will cause overheating of the plug resulting in power loss, detonation, pre-ignition and possible engine damage.
Heat range numbering systems are different between plug brands. On a DENSO plug the lower the number, the hotter the plug so the higher the number, the colder the plug. Other Japanese companies use the same system, but European or United States companies use a numbering system that reads in the opposite way.
these plugs are what i am putting in when it comes time to get new plugs ..
$48 is a good price .. i think HKS sells these rebranded for $23 each!!