Why would I need a higher heat range spark plug? I have a 2010 R55 Clubman John Cooper Works. Looking to buy your stage two kit and don't know if I need the higher heat range.

 

Here is some info on plugs and tunes http://jmtcperformance.com/tech-info...ing-and-setup/

 

A colder heat range plug will reduce the chance of pre-ignition. When you increase performance both cylinder pressure and temperature increases. The spark plug protrudes into the combustion chamber and is subjected to the increased heat. Without a colder range plug, heat can accumulate in plug to the point it can ignite the intake charge before it fires.

NGK 1422 - One heat range colder. In addition the gap is reduced from .032" to .024" which will reduce the chance of misfire under high boost.