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NGK IRI (WAY)(TOP)(MAC) plugs have a 0.6mm iridium tipped center electrode with a tapered cut ground and are sold under the name Iriway, Iritop and Irimac throughout Japan and other select countries. In the US and Europe these same plugs have been released under the IX Iridium Series and can be identified by their alphanumeric part numbers. The list below shows appropriate interchanges. The IRI Series and IX Series are produced in the same NGK factory. They are identical in construction, with packaging and marketing being the only difference.
|IRI Series||=||Alphanumeric Part#|
|(Not available in the US. Can use BKR8EIX, which is identical but is ISO height instead of JIS)|
|(Not available in the US. Can use BKR9EIX, which is identical but is ISO height instead of JIS)|
NGK IRIMAX Series plugs have a fine wire iridium center electrode with a platinum chip on the ground electrode. They are constructed to provide both performance and long life. This plug type is available in the US under the Laser-Iridium Series, which includes "IFR" "IGR" "IJR" "ILFR" "ILTR" "ILZR" "IMR" "ITR", etc. plugs. These part numbers have the same construction, and, like the IRIMAX, offer performance over their extended life (100,000 miles). So if the catalog shows an "I" series plug is available for your car, it is essentially the best spark plug made for both high performance and long life (just like the IRIMAX).