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NGK Iridium IX Performance Spark Plugs (79-82 5.0L; 87-93 5.0L; 94-95 GT)

Market Price $79.99 You Save 13% ($10.00)
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$69.99 (set of 8)

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  • Item 64005
  • MPN# 7559

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    Features & Details

    • Iridium Tip for a Constant Stable Spark
    • Improves Fuel Economy and Lower Emissions
    • Heat Range: 4
    • NGK Part# 7559
    • Fits 79-82 5.0, 87-93 5.0 LX/GT, and 94-95 GT
    • Sold as a Set of 8
    High Performance. Keeping your Mustangs high performance engine running smoothly and efficiently is important, so routinely replace your old weak plugs with a new set of NGK Iridium IX Performance Spark Plugs for constant reliable spark power. The Iridium IX plugs from NGK will provide improved throttle response, fuel efficiency, lower emissions, and will reduce fouling.

    Superior Materials. NGK Iridium IX Performance Spark Plugs feature a copper core electrode for its superior conductivity and an iridium tip (which is 6X harder than platinum) for it's extremely high melting point, perfect for keeping your Mustangs high-performance engine running at it's peak. And as an added bonus the Iridium IX plug features Trivalent Metal Plating for it's superior anti-corrosion and anti-seizing properties.

    Application. This set of eight (8) NGK Iridium IX Performance Spark Plugs are specifically designed as a direct fit replacement for the 1979-1982 5.0 V8, 1987-1993 5.0 LX/GT, and the 1994-1995 GT Mustangs equipped with the 5.0 liter V8.

    Fitment: 1979 1980 1981 1982 1987 1988 1989 1990 1991 1992 1993 1994 1995 Details

    What's in the Box
    • (8) Spark Plugs
    Installation Info
    Tech Specs
    Will it fit my Mustang?

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    7 Questions / 10 Answers

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    Will these work well for TFS Aluminium heads on a 306 Dart Block pushing a Vortech at 10 PSI?


    • Unfortunately we do not have enough information to determine how these NGK Iridium IX Performance Spark Plugs would work with your setup. Please contact our Customer Service department, or your tuner so that your complete setup can be discussed, and a spark plug recommendation can be made.

      Rob D

    Helpful (0)

    I have a 1992 347 with stock block eldlebrock rpm performer heads will these work and what shoukd the gap setting be.


    • A custom setup such as the one you have may require careful testing and gapping, I would contact a local shop that specializes in performance tuning in order to determine the proper heat range and gap for your application before ordering the NGK Iridium IX Performance Spark Plugs.


    Helpful (0)

    Would these work for a 1985 5.0 Gt convertible?


    • For your 85 GT, you will need the NGK Iridium IX Performance Spark Plugs (83-85 5.0L), item # 64017, (


    Helpful (0)

    What spark plugs would you recommend for my boosted 5.0 running 5-7 pounds and a mild top end and stock bottom


    • I would recommend at least a one step colder spark plugs to ensure the spark plugs work well thermally. Unfortunately, we do not carry a spark plug for your generation for forced induction applications, however, I would highly recommend a NGK plug on almost any application. If you are looking for a NGK plug specifically, please remember that the heat rating of each NGK Spark Plug is indicated by a number; lower numbers indicate a hotter type, higher numbers indicate a colder type. This may be opposite information from brand to brand, so it is important to check.


    Helpful (0)

    does anyone know that gap size they come in i know tthey come pregapped


    • i do not know what they come as but any plugs that you get pre gapped or not could have changed during shipping. so i would gap them again before installing them.


    Helpful (0)

    Anti-seize, yes or no? Should I use anti-seize with these or not and which one do you recommend?


    • According to NGK, "the use of anti-seize compounds on spark plug threads that have a metal shell plating (i.e. Zinc or Nickel plating) may allow the installer to mistakenly over-tighten the spark plug". To answer your question, skip the anti-seize. You'll be fine. NGK's plating is already designed to prevent corrosion and seizure.


    Show 4 more answers Helpful (0)

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    Customer Reviews (21) Write a Review

    Overall Rating 5.0

    out of 5 stars

    Installation Time:Afternoon

    Installation Cost:0-$100

    • Performance Gain 4.857143 4.9
    • Fit 4.857143 4.9

    • 5/5

      Installation Time: Less than 1 Hour

      November 30, 2017

      1994 mustang gt NGK Spark plugs

      NGK performance Plugs work great! Will buy again if needed.


      Year: 1994 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Afternoon

      October 16, 2017


      These Sparks really livened my Fox up, both in response and power!


      Year: 1989 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      August 23, 2017

      Great Spark Plugs!

      I replaced my distributor cap and rotor, plug wires, and decided to change the plugs too while I was in there. The plugs I took out weren't bad at all, maybe a few thousand miles on them, but wow my car idles so much better and the engine runs so much smoother in general. You can't go wrong with these NGK iridium plugs I have them in my ranger as well. The difference is night and day


      Year: 1990 Submodel: LX

      Helpful (2)

    • 5/5

      Installation Time: Afternoon

      June 08, 2017

      spark plug

      Very easy to install. Several people will still say go with motorcraft because its what ford takes and I was seconding guessing this product but after installing, I notice a big differents in gas, ignition and so forth. Honestly it was worth the cash.


      Year: 1994 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      February 25, 2017

      Great buy

      Easy to put in. No need to adjust the gaps for me and it runs smooth what more could you want.


      Year: 1988 Submodel: LX

      Helpful (1)

    • 5/5

      August 17, 2016

      Great plugs!

      Great plugs felt a difference right away, throttle feels more responsive!


      Year: 1988 Submodel: GT

      Helpful (3)

    • 5/5

      July 10, 2016

      True testimony of the ngk experience

      I had to try these after all the good I've heard about them, and now I'm a true believer. These little guy's made a world of difference in my 95 gt. The idle is so smooth now, the hesitation disappeared and man, I tell you that when I get on it. Lets just say, It's a real go getter again.


      Year: 1995 Submodel: GT

      Helpful (2)

    • 4/5

      Installation Time: Afternoon

      April 04, 2016

      Best spark plugs

      Excellent plugs and it's definitely worth the money. Installation was a breeze, they thread right in with no problem. My 5.0 fired right up and runs twice as good as what it did before. I can really get into the gas and I can feel the difference from those old plugs that was in there before. I recommend these to anyone trying to bring their 5.0 back to life


      Year: 1988 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Afternoon

      January 04, 2014

      NGK spark plugs

      Great plug! Good performance upgrade. Works great with my upgraded ignition system!


      Year: 1994 Submodel: GT Hilton Head Island, SC, USA

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      May 07, 2013

      Great Set of Plugs

      My 88 was having trouble keeping its power in the higher rpms until I installed these sparkplugs and man what a difference! The idle is a lot smoother and it burns a lot cleaner. You can even hear the difference when you accelerate. Defiantly worth it.


      Year: 1988 Submodel: GT Stuart, FL

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      November 24, 2012

      made a huge difference.

      I changed out my whole system. These are a great addition. My old plugs were looking worn and with shorty headers I wanted to prolong the life of my plugs. I could feel a difference after the install and you will too.


      Year: 1994 Submodel: GT Malvern, PA

      Helpful (2)

    • 5/5

      Installation Time: Afternoon

      October 20, 2012


      i like these plugs and the fit is a lot better then the ones i had before. also the only reason it looks over 2 house to do these plugs was #1 my old plugs were stuck and had to be forced out #2 cylinder number 4 (back, left plug) was a pain because of the angle of my header.


      Year: 1992 Submodel: GT Maryland, USA

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      August 31, 2012

      Saves you gas and better throttle

      I had these cheap auto lite plugs. They were ok. I would get 125 miles to an empty tank. Put these in, car starts better, accelerates better and I get 155 to an empty tank..(93 octane with sct tune) so its worth getting. Shouldn't take more than an hour to out in.


      Year: 1989 Submodel: GT Orlando fl

      Helpful (3)

    • 5/5

      Installation Time: Shop Install

      Installation Cost: 0-$100

      July 02, 2012

      This product gave me back my Mustang

      The performance of my car was greatly improved. I like stepping on it and feeling the gs. Anxious to see if the gas mileage will improve. I think it will just from the way the car is performing.


      Year: 1995 Submodel: GT New Hampshire

      Helpful (3)

    • 5/5

      Installation Time: Afternoon

      June 29, 2012

      NGK all the way!

      Man, they made my 'stang sound like it had a whole different mill in it! It's got more pop to it everytime it fires!


      Year: 1991 Submodel: Other Orange, TX, USA

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      April 27, 2012


      I just installed these spark plugs last night in my 94 gt and I still can't believe how much of a difference I've felt at idle, much smoother, and most importantly across the rpm. I highly consider you upgrading to the iridium spark plugs! Oh and I also installed new spark plug wires with a new distributor cap (which matches the color of my wires) and rotor. Great buy!


      Year: 1994 Submodel: GT West Palm Beach, FL, USA

      Helpful (3)

    • 5/5

      October 14, 2010

      NGK Iridium plugs

      The plugs work great. Great engine start and car feels a little more responsive.

      Carl Chambers

      Helpful (6)

    • 5/5

      October 14, 2010

      NGK Iridium IX Performance Spark Plugs 5.0

      a true love hate relation ship, they work great but after racing around they like to sputter at low rpm's, but works a lot better then stock!

      cody K

      Helpful (2)

    • 5/5

      April 15, 2010

      NGK Iridium IX Spark Plugs

      These plugs are the jimmy jam. My pony is runnin so smooth now. I could instantly feel the difference from the time I started it up. Super responsive plugs. A++ in my book! Thanks AM


      Helpful (3)

    • 5/5

      April 08, 2010



      Hiram Maldonado

      Helpful (2)

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