NGK Laser Iridium IFR6T11 Spark Plug vs DENSO Iridium Power IK20 Spark Plug

Both are 14 mm, 19 mm reach iridium plugs with a 1.1 mm gap and a 16 mm hex, so they physically interchange in many engines. The NGK IFR6T11 is a laser-welded, fine-wire iridium plug built as an OE replacement, and it is the safer pick when your owner's manual specifies an NGK iridium plug. The DENSO IK20 uses a 0.4 mm iridium center electrode with a tapercut U-groove ground electrode and a 5,000 ohm resistor, and owners report smooth idle and strong response. Heat ranges differ (NGK 6 versus DENSO 20), so match the plug to your engine's spec rather than swapping brands freely.

• Choose the NGK Laser Iridium IFR6T11 if your vehicle calls for an NGK iridium plug with heat range 6, or you want a laser-welded OE-style plug and a set of six for a full tune-up.
• Choose the DENSO Iridium Power IK20 if your engine specifies a DENSO 20 heat range plug, or you want a 0.4 mm fine-wire electrode and buy plugs individually.