Spark Plug for 4AGE BT 20v engine is IK20.
For further information, u may refer this website
http://www.globaldenso.com/en/products/aftermarket/plug/basic_knowledge/heatrange/index.html
Our Ketua Darjah's awesome ER34 was recently sighted at TAS 2011.. Now sporting a GT-R emblem at the front.. Senyap2 dia fully convert to GT-R spec.. :biggrin...