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Racing Spark Plugs (03-04 Cobra; 07-14 GT500)

Item 525503
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Ship to: Ashburn - 20149
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      Product Information

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


      • Perfect for Boost & Nitrous Applications
      • Chromium Nickel Alloy Tip for a Constant Stable Spark
      • Improves Fuel Economy and Lower Emissions
      • 1 Heat Range Colder
      • Autolite Part# AR103
      • 14mm Thread Pattern
      • Spark Plug Reach 0.708"
      • Fits 2003-2004 SVT Cobra and 2007-2014 Shelby GT500
      • Sold as a Set of 8


      High Performance. Keeping your Mustangs nitrous or force inducted engine running smoothly and efficiently is important, that is why it is critical to choose the correct spark plugs for your application. These Autolite Racing Hi-Performance Spark Plugs are one heat range colder than stock making them perfect for supercharged Mustangs that are running additional boost.

      Superior Materials. Autolite Racing Hi-Performance Spark Plugs feature a copper core electrode for its superior conductivity and a chromium nickel alloy tip for a constant stable spark, perfect for keeping your Mustangs high-performance engine running at it's peak.

      Application. This set of eight (8) One Heat Range Cooler Autolite Racing Spark Plugs are specifically designed for the 2003-2004 SVT Cobra and 2007-2014 Shelby GT500 Mustangs that are running more boost.

      Fitment: 2003 2004 2007 2008 2009 2010 2011 2012 2013 2014 Details

      MPN# AR103

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (5)

      Write a Review

      Ratings Summary

      4.8 out of 5 overall rating from 5 customers

      Installation Time: Less than 1 Hour

      • April 05, 2019

        5 2010 GT500 - MartinR Installation Time: Less than 1 Hour

        Great spark plugs

        Their racing spark plugs nuff said. Good for street and track. Gap to fit and speed away

        Helpful (0)
      • December 17, 2017

        5 2003 Cobra - AngeloV Installation Time: Less than 1 Hour

        Autolite spark plugs

        I was having a bogging/missfiring issue . These plugs fixed that on my 03 Cobra , I am only running 12 pounds of boost on my pores Eaton So I highly recommend this for anyone running low boost.

        Helpful (14)
      • December 14, 2015

        4 1998 Cobra - Eric Installation Time: Less than 1 Hour

        1998 cobra 03 cobra long block

        The plugs when in nice and easy seem like my car idles a whole lot better clean burn smell to exhaust

        Helpful (14)
      • November 19, 2015

        5 2008 GT500 - Tmoney Installation Time: Less than 1 Hour


        Very good product would recommend for any one running a lot of boost in ther car

        Helpful (16)
      • October 06, 2014

        5 2003 Cobra - KellyS Installation Time: Less than 1 Hour

        Dyno day

        Put these in my cobra before i threw it on the dyno. Ran perfect. Would use these for a long term spark plug if you daily drive ect. but they are the best to use for getting the highest dyno numbers.

        Helpful (15)

      Questions & Answers (5 answers)

      5 Top Rated Questions

      I have an 08 shelby vmp gen 3R supercharger,jlt 123 cold air,I'd 1050x fuel injectors and 2.6 pulley....would these be the plugs you recommend and what gap would you use...thanks

      Will these work on a 03 gt?

      • These Autolite Racing Spark Plugs are intended for 03-04 Cobras and 07-14 GT500s. For a full selection of spark plugs for your 2003 Mustang GT, please click the link below.

      Helpful (0)

      Can These Spark Plugs Hold Up to 700 Hp ? Or no ? I need a spark plug that can because I have the 2.3 FRPP TVS blower on my car

      • Yes, you could use these spark plugs for this application and with this blower!

      Helpful (0)

      Hello, can this spark plugs be used on a 2003 Mach 1? car is literally stock, thanks.

      • The Autolite Racing Spark Plugs would not be ideal for your 2003 Mach 1, as these are one heat range below stock. This makes them ideal for boosted and nitrous applications, or naturally aspirated builds where horsepower has been significantly increased with both bolt ons, and engine work such as heads, cams, etc.

      Helpful (0)

      My Shelby book refers me to the emission control decal to get Spark Plug Gap. WELL; it refers me back to the Shelby Book.I see you mention Spark Plug Reach....Is this actually the GAP? I have a 2007 GT5OO.I have the AP103 Plugs...THANKS...

      • Spark plug gap and spark plug reach are slightly different. Spark plug gap would be a measurement of distance between the center and side electrodes on the plug, whereas the spark plug reach is the length of the plugs threads.

      Helpful (0)
      Post Your Question

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (8) Spark Plugs

      Tech Specs

      Will It Fit My Mustang

      • Cobra - 03, 04
      • GT500 - 07, 08, 09, 10, 11, 12, 13, 14

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