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

16 Reviews
Our Price


(set of 8)
  • Item #64005
  • MPN# 7559

  • Market Price $79.99
  • You Save 13% ($10.00)
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  • 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
Will it fit my Mustang?
  • Foxbody - 79, 80, 81, 82, 87, 88, 89, 90, 91, 92, 93
  • GT - 94, 95

Fits 5.0L V8's Only

Most Helpful Reviews


when i put these plugs in my 5.0 Cobra they fired up like and bat out of hell!! They work well with k&n filter and flowmasters, I can feel it breathing better probably added a couple of horses ill know ...

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Helpful (4)

NGK Iridium plugs

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

Helpful (4)

Overall Rating 4.9 out of 5 stars
Read All 16 Reviews

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4 Questions / 11 Answers

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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.


    Good Answer (0) (0)

Answer This Question I need this answered (0) (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.


    Good Answer (1) (0)

Show 4 more answers Question Resolved

Spark Plug Gap? Are the plugs already gapped or will i need to gap them?


  • all plugs come from the factory pre-gapped... be sure to put anti-seze on all the plugs....


    Good Answer (2) (0)

Show 3 more answers Question Resolved

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.


    Good Answer (0) (0)

Question Resolved

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Customer Reviews (16) Write a Review

Overall Rating 4.9

out of 5 stars

Installation Time:Afternoon

Installation Cost:0-$100

  • Performance Gain 4.777778 4.8
  • Fit 4.777778 4.8

  • 5/5

    February 27, 2010


    when i put these plugs in my 5.0 Cobra they fired up like and bat out of hell!! They work well with k&n filter and flowmasters, I can feel it breathing better probably added a couple of horses ill know for sure when i put it on the dyno. great product good discount

    james johnson

    Helpful (4) (0)

  • 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 (4) (2)

  • 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 (1) (0)

  • 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 (1) (0)

  • 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 (1) (0)

  • 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 (2) (1)

  • 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 (0) (1)

  • 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 (0) (1)

  • 5/5

    April 08, 2010



    Hiram Maldonado

    Helpful (1) (3)

  • 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 (1) (4)

  • 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 (0) (1)

  • 5/5

    August 17, 2016

    Great plugs!

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


    Year: 1988 Submodel: GT

    Helpful (0) (0)

  • 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 (0) (0)

  • 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 (0) (0)

  • 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 (0) (0)

  • 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 (0) (0)

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