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These NGK TR55IX Iridium plugs are a good long-life iridium plug. My 1995 Corvette LT1 is a pain to change spark plugs so I wanted to get a long life plug, these fill the bill perfectly. NOTE: the pictures show crush washer seats, which is incorrect. These plugs have tapered seats as required by the gen 2 SBC LT1 engine.
Installed in 2007 Ford F150 4.6L. Ford didn't make it easy to change out the spark plugs on this vehicle. It took me about 2 hours on the driver side and 1 hour on the passenger side to remove old plugs and put these babies in. Plugs are pre gapped to the correct size but I verified each one before I put them in. Truck runs smoother and has better acceleration.
Bought these plugs to replace platinum plugs that lasted about thirty thousand miles.I did have to gap all of them to specifications.That is a trivial matter.I bought these plugs because according to my research they are made of the hardest material out there on the market for plugs.I' am expecting at least 70,000 miles before change out,that I can not attest to only time will tell.However I did feel a significant difference in performance. I replaced the plug coils with summit high performance coils because I still had an occasional engine miss fire after replacing the plugs.Since replacing both spark plugs and coils,engine runs smooth,quite, no more engine miss fire,much improved engine performance and improved mileage per gallon.If you replace your plugs and still have engine performance issues,change your spark plug wires and or coils depending on what your engine uses.Replace all of them at the same time not just one or two.These items were replaced on a high performance Crown Victoria engine.GOT IT--GET IT.
Really brings the truck to life. I can’t believe it! These paired with the MSd blaster coil packs completely changed my 4.6l F-150. Combined with tune, intake, exhaust, I’m literally putting 5.4’s in the dirt. I’m amazed how much power can be brought out of the 4.6l fords with just a few quality parts and a custom tune.
Engine running rough after installed. Ran for 5 minutes and dies out. Waited till later and same thing happened. I put OBD meter on it and it shows PO300 code stating random misfires. It's all of them because this is not the right plugs for my car even though the Amazon garage note says "this fits your car".
Installed in my 2006 F150 4.6 2 valve V8, along with MSD BLASTER COILS. Super smooth idle, better pick up and smoother shifting automatic transmission. Just installed, so will give update if anything dont last. Definitely recommended.
I called tech-support when I received these plugs because I noticed the heat range number was much hotter than stock. Tech-support reassured me they use a different number system and they are a match for stock. They were not.
I put these in my 1953 Chevy Pick up. It has a 350 in it from the 70's and these plugs made a noticable difference. I don't mean that it sounded 2% better, I mean that it was VERY noticable how much smoother it ran. I assume it is because these plugs burn more efficiently so they get more power from the availible fuel, but whatever the reason, they are well worth the money. And - Irridium is so hard that I don't plan on replacing the plugs again for the rest of the time I own the truck so the money is well spent.