****** - Verified Buyer
4.5
works as it should havent had them long enough to do say to muchBought 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.I used the first 8 of these NGK Iridium plugs for just over 100,000 miles. I know it was time to change them when my truck wouldn't start on the first crank.With the new plugs, my truck is back to normal.These work just fine in my Impala SS, though I'm not technical enough to know how much of a performance or reliability improvement they represent. Installed with Taylor Cable ThunderVolt wires, using electric grease on the insulators and anti-seize on the threads.I wasn't careful enough on installation and evidently put too much sideways pressure on the plugs while tightening. A couple of my plugs are tough to get to (transverse V8) and I wasn't careful enough and cracked the ceramic insulation on one of them. Didn't realize until I started to troubleshoot a misfire code. (P0302.) But I imagine the same care would be required for any plug.Happy with this purchase.NGK spark plugs always perform well I have never had a problem with themI use these plugs all the time on my 2003 mustang gt. Overall great value & product for your money & your carThese plugs are worth the extra cost which wasn't that much more than the standard platinum plugs for my vehicle. Improved power, starting and fuel mileage. Would recommend these.At the time of purchase, (and at this writing), the Amazon Garage 'Fitment' incorrectly indicated these NGK TR551X / 7164 spark plugs fit my 1992 Chevy C1500 w/5.7L (gasoline) engine ... they do not. The electrode 'reach' (.75") is too long for this early GM engine application. Installing these longer-tip plugs may cause serious engine-piston damage. 'One Star' rating is not for quality, NGK manufactures excellent product.Arrived on time and as described
