Denso Iridium Power Spark Plugs

Was gonna try some NGK Iridium plugs but my Bro Chris from Pentagon Enterprise recommended me the Densos instead. Per Chris the Denso Iridiums make more power than the NGK IX series but don't last as long. Chris reckons the plugs should be changed every 30K km or so. I know a decent copper plug would be just as good but hey.. the anaemic QG16DE engine is going to need all the help it can get for more oomph.

Settled for heat range 6 Denso Iridium Power plugs. The stock plugs are heat range 5 (NGK BKR5E) . Decided to go for heat range 6 plugs as this should hopefully give me a little more on top while eliminating pinging when whacking the engine. Used NGK Iriway 7 heat range on the SP but that had 11.9 compression ratio. Do not recommend anything higher than 6 for daily driver and lightly modded engines for risk of fouling your plugs. In addition the cold plugs would also encourage carbon buildup due to not enough heat. Denso has their own heat range denomination btw. A NGK 5 heat range plug would be 16 for the Denso, 6 would be 20 and 7 would be 22 and so forth. You can read up more about an iridium spark plug's advantages, the other plug ranges and tech details in Denso's very detailed webpage. Besides the Iridium Power range there is also Iridium Tough, Iridium Plus and Iridium Racing each with their specific advantages.

Pix below of the Denso packaging. Each plug has it's own mini box and all 4 mini boxes go into one larger box. Part Number for Heat Range 6 (IK20) plug is 5304. The part number for IK16 plug is 5303 while IK22 is 5310. A resistor plug is must for QG series engines.

Pix of the plug

So how does it feel and most importantly are there any power gains from the butt dyno? I'll have to say the power increase while minimal can be felt. The plugs nicely complemented the K&N filter giving a better pull throughout the rev range. Perhaps the best satisfaction is when my tyre guy who drives Sentras everyday actually asked me if I did anything to the engine as my car accelerated better than a stock QG16DE. Still honestly I would say 1-2hp at the most for the plugs. This would mean about a 3hp increase for nearly 400 smackers. Blardy expensive but hey welcome to the world of trying to make power from an NA engine.