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NGK Iridium IX Spark Plugs (Mid 08-10 GT)

Item 64068
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$89.99 (set of 8)

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      Review & Installation Video

      These are the NGK iridium spark plugs for mid-2008 to 2010 GT and Bullet Mustangs. These NGK iridium spark plugs have a heat range of six, which is the same heat range of the factory plugs. Now being the same heat range means that these plugs are gonna be a good option for those that have a stock setup or one with basic bolt-ons. If you have a forced induction Coyote, you'll need to make sure that you go with a colder heat range plug. So, a turbo, super charger, nitrous build would need the step cooler plug. But if you have a naturally aspirated build and you're looking for a performance plug, I would suggest these plugs, since they have the same heat range and these are a good stock replacement upgrade. I will say though, that these are for the Mustangs that are equipped with the brown coil boots only. The install for spark plugs is very easy on the Coyote. It's a one outta three wrenches in the difficulty meter, and you can plan on spending about a half an hour's time. So, heat range is something that's important to pay attention to when you're shopping for spark plugs. Different builds and setups require different heat ranges. It all depends on your mod list. The heat range of the plug is a range where the plug works well thermally. And of course your modifications, or lack thereof, will determine the temperature where the spark plug will be operating. You wanna make sure you're getting a plug in the right heat range, so the plug can function normally and so you won't have fouling or pre-ignition. The heat range on this plug is a six, and the way NGK labels their plugs is the lower the number the hotter the type of plug. The higher the number, the cooler the type of plug. These spark plugs still have a copper core electrode and the iridium is in the tip of the plug. Iridium is a very strong material and has a very high melting point which makes it perfect for performance-based applications. The core in the iridium tip are gonna be determining factors of the heat range of the plug. When it comes to price, you can expect to pay just south of the 100 dollar mark for a set of eight plugs. This is the same as what you can expect to pay for other brands of plugs, so I wouldn't say that the price is crazy here. Your other options include: Ford Performance, Autolite, Ford Motorcraft and Brisk makes an offering for boost that are also very close in price. So the NGK here isn't your only option, but they are your only option if you're specifically looking for an iridium plug. As far as the install goes, this is an easy install and it's a one outta three wrenches in the difficulty meter. You'll need a few tools and some anti-seize for the spark plug threads. The coils will need to come off so you can disconnect the electrical plugs and unbolt each coil pack. Once the coil packs are out of the way, you have access to the spark plugs. If you want, you can use some PB Blaster to help loosen the plugs up before you dive in with your socket to remove the plugs. I would suggest putting some anti-sieze on the threads of the new spark plugs and make sure the plugs are all gapped the same before you install them. Once you've swapped all of the plugs, reinstall the coil packs, plug them back in, and that's all it's gonna take. Wrapping things up here, these are the NGK iridium spark plugs for mid-2008 to 2010 GT and Bullet Mustangs. As always, you can check them out more online right here at

      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • Iridium Tip for a Constant Stable Spark
      • Improves Fuel Economy and Lower Emissions
      • Heat Range: 6
      • NGK Part# ZNAR6IX-11; NGK Stock# 372
      • 12mm Thread Pattern
      • Sold as a Set of 8
      • Fits 2008-2010 GT and Bullitt Mustangs w/ Brown Coil Boots


      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 for the 2008-2010 GT and Bullitt Mustangs equipped with Brown coil boots only.

      Fitment: 2008 2009 2010 Details

      MPN# 372


      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (44)

      Write a Review

      Ratings Summary

      5.0 out of 5 overall rating from 44 customers

      Installation Time: Afternoon

      Installation Cost: 0-$100

      • November 03, 2019

        5 2009 GT - BlackPearl Installation Time: Afternoon

        Better than OEM

        About to hit 60k so I decided to do this and the fuel filter. I'm lucky to have a 2009 with one piece plugs so no issues breaking. After these and the filter, the car is more responsive, better idle, and no sluggish, dragging feeling I was starting to notice. Nice and peppy now.

        Helpful (1)
      • October 23, 2019

        5 2009 GT - Tarik Installation Time: Less than 1 Hour

        Spark plugs

        Great spark plugs very easy install, already gap to specs, definitely recommended to anyone looking for a good spark plugs

        Helpful (1)
      • October 19, 2019

        5 2008 GT - Guywithcar Installation Time: Less than 1 Hour

        Great but don’t fit the older 4.6

        Ok so I got these but no go had to send back and never got refunded for them but it’s cool should have read more they only fit the new 4.6 but no big deal

        Helpful (1)
      • August 29, 2019

        5 2009 GT - RobertP Installation Time: Afternoon

        NGK Iridium IX plugs

        I have the thumper cams and it was time for a tune up. The motorcraft plugs were out of stock everywhere and wanted to do tune up right away so went with Iridium plugs. Not disappointed. I wouldn’t say I gained horsepower but that it restored horsepower that I didn’t realize I had lost. I could feel it immediately. Car idles great and cold starts reach smooth idle much faster. I would buy them again.

        Helpful (1)
      • March 08, 2019

        5 2010 GT - PeterW Installation Time: Less than 1 Hour

        Spark plugs

        Great product. Improved the idle and performance. I would recommend these plugs!

        Helpful (4)
      • January 17, 2019

        5 2008 Bullitt - PaulE Installation Time: Full Day

        Works great.

        I gave these a try since it has a really good reviews. Didn't disappoint.

        Helpful (2)
      • November 19, 2018

        5 2008 GT - Chrisj Installation Time: Less than 1 Hour

        150,000 miles and still going strong!

        They are plugs. I also did msd coil packs. between the two the car is running much better.

        Helpful (1)
      • September 24, 2018

        5 2010 GT - The4p6thatcould Installation Time: Less than 1 Hour

        excellent product for the price.

        as said in the title, good stuff you can't beat the price.

        Helpful (5)
      • August 13, 2018

        5 2010 GT - Arodnasty Installation Time: Less than 1 Hour

        Excellent spark plugs. Best bang for your buck.

        Spark plugs feel and look like good quality. Car runs Awsome.

        Helpful (5)
      • August 08, 2018

        5 2008 GT - NytollaW Installation Time: Less than 1 Hour


        It was perfect on my end. Everything for just well

        Helpful (3)

      Questions & Answers (18 answers)

      5 Top Rated Questions

      What is a Brown Coil Boot? I see that I must have it to install these plugs so what are they? I have a 2010 GT

      • The boot coil color changed some time in 2008 from black to brown. Your 2010 would have a brown boot. Hope this helps!

      Helpful (3) Show 1 more answer

      it says to drop 1 heat range for every 75-100 hp added. what is the factory heat range?

      • The NGK Iridium IX Performance Spark Plugs would share the same heat range of the OEM plugs, coming in at heat range 6.

      Helpful (1)

      Is the gap of these NGK plugs set to 0.40-0.50? It seems like a lot of people have installed their new NGK plugs without checking the gap but have had no problems.

      • We do not have the spec at what these NGK plugs are set to out of the box, they would be close to factory spec but we always recommend double checking the plug gap before installation to ensure proper performance.

      Helpful (1)

      So i recently bought an 07 GT/CS 4.6L 3v, The car did not come stock, i popped the hood and reviled the fact that the 4.6 was equipped with a full set of the MSD Blaster pack on plug coil packs, I have no clue if these plugs will work because i have never seen the original boot or coils, will they fit?, The reason i ask is mainly because i am replacing my plugs and possibly my packs as well, due to miss-firing in cylinder 3 and another random cylinder as the dealers told me after a diagnostic, the car also has high flow cats and JBA headers not sure if they are longs or shorts tho, i noticed the problem after my first test drive and usually happens only on full throttle, i was running 93octane pump gas and using 112 octone booster when it started getting really bad.

      • Your 07 would utilize the of-early 08 style plug design. The only year where the color of the coil boots would need to be checked would be a 2008 model year car.

      Helpful (1)

      Will the NGK Iridium plugs work with MSD coil plug set? Will these plugs work with MSD coil plug set?

      • Yes it will

      Helpful (1)
      Post Your Question
      10 More Questions
      Are these good for a turbo set up ? If not can u send me a link for a good set u have a 2006GT with a 2008 motor 1 answer
      Would these fit on my 2006 GT? Thanks 1 answer
      Are these one piece design? 1 answer
      Can these fit on 2005 mustang GT? 1 answer
      Will these fit my 06 mustang gt? 1 answer
      is the gap preset 1 answer
      Do these plugs require a tune after installing with a set of MSD blaster coil plugs 1 answer
      So my mustang has recently thrown a random misfire code and was thinking about going with MSD coil packs as I've heard that would help. Any ideas of what spark plugs would be a good match for the MSD coils? By the way, the car has FRRP intake manifold and Hot Rod Cams, GT500 throttle body, K N cold air intake and BBK shorty headers. 1 answer
      Since it says 08-10GT I probably can't use these in my 07 GTCS then can I? Or will it be able to be used with no problems? If not which plugs do you think I should go with here on AM? 1 answer
      I want to add a nitrous kit and run 150 shot what are the correct plugs will I need and can I get them at AM my car has a cai with a bama race tune and should I go with 4:10 or 3:73 gears 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (8) Spark Plugs

      Tech Specs

      Will It Fit My Mustang

      • Bullitt - 08, 09
      • GT - 08, 09, 10

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