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NGK V-Power Spark Plugs - Heat Range 6 (03-04 Cobra; 07-14 GT500)

Market Price $29.98 You Save 17% ($4.99)
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$24.99

FREE Shipping on orders over $49
  • Item 525094
  • MPN# TR6

In Stock Ships same business day. Choose options to add to cart

Features, Videos & Details

  • Perfect for Stock Boost
  • V-Groove Technology
  • Improves Fuel Economy and Lower Emissions
  • Heat Range: 6
  • NGK Part# TR6; NGK Stock# 4177
  • 14mm Thread Pattern
  • Spark Plug Reach 0.690"
  • Fits 2003-2004 SVT Cobra and 2007-2014 Shelby GT500
  • Sold as a Set of 8

Review & Installation Video

Justin: Hey, I'm Justin with AmericanMuscle.com and this is the Stage 2 Power Pack Bolt-On Build-Up for all 2007-2009 GT500s. This Power Pack is for the GT500 owners who have already taken care of some of the basic bolt-ons; your cold air intakes, your tunes, and are looking for more power out of your supercharged 5.4 liter. Now if you guys are looking for more power out of your Mustang, whether it's a GT500, a GT, or a V6, be sure to check out some of our other Bolt-On Build-Ups by subscribing to our YouTube channel if you haven't done so already. This entire pack is centered around a very popular supercharger mod that's going to increase our boost and therefore increase the horsepower on our GT500. However, just like anything else in the forced induction world, you can't just add more boost without addressing other key areas of your ride to ensure you're getting the most out of each mod, but more importantly to ensure the safety of your motor. So first, let's get to everybody's favorite topic, more boost. The first mod in our Power Pack consists of the Metco Motorsports 2.6 Inch Upper Pulley. Now a smaller pulley like the Metco here is always a very popular choice with supercharged applications because what it's going to allow you to do is spin that stock blower much faster, resulting in more boost. In fact, we should be looking at three to four pounds of additional boost compared to the stock three inch pulley. The Metco itself is a very nice piece and is actually very popular with other GT500 owners here on the site. In fact, if you want, you can just click on the link below to read up on some of the reviews. Now the design is a two piece design, so you have a hub that presses onto the blower shaft first, and then the actual pulley bolts to the hub using the included hardware. This is just basically going to make any future pulley swaps a complete piece of cake. I really can't wait to see what a few extra pounds of boost are going to do to our power number, and best of all, that factory Eaton blower should really be screaming. With the pulley out of the way, let's talk about some of those other supplementary mods that I told you guys about at the beginning of the Pack. Now again, you can't just bolt up a pulley and go without addressing some other areas. Case in point, that smaller pulley has now created some excess slack in our belt which basically our factory idler will not be able to keep up with. What this is going to result in is dreaded boost and power robbing belt slippage. Enter the Metco Double-Bearing Auxiliary Idler Pulley Kit which we also installed on our '08 here. Now this is going to take up the extra slack created by the smaller 2.6 inch pulley and just create plenty of belt wrap to prevent any belt slippage, and more importantly it's going to ensure that those boost levels stay rock solid all the way through the upper RPM range. On top of that, the double bearing construction will ensure a little bit more durability over time, it might actually be a little quieter, and for a few bucks more it's really a no brainer. Finally there's one more part to go over before we bring in Mike J from Bama to tweak the tune a little bit for us, and of course turn the rollers one more time. With that pulley in place, we're really going to be spinning our blower a lot faster than we were before which of course will lead to more boost meaning we had to address our spark plugs. So we installed the NGK TR6 Plugs which really are the go-to spark plug for any Shelby owner who is upping their boost. They're a one heat range colder plug compared to our stock plugs which will help avoid any possible detonation. An important note, just make sure they're gapped correctly before install to avoid any spark blowout. Definitely recommend doing these plugs or something similar whenever you really start cranking up the boost like we are here with the '08. Alright, well with all the new parts in place, we have Mike J from the Bama Performance Team in here working on the new tune for us for all increased boost that we're going to be seeing thanks to that smaller pulley. Now Mike, obviously the car's going to be seeing a lot more boost than we were before. How does that affect things on your end? Mike J: Well basically with the higher boost levels, we're going to be seeing right around 12 to 13 pounds. I've already gone ahead and made adjustments to the ignition timing tables to make sure that we're not going to see any detonation at all. I'm then basically just looking at air-fuel ratio to make sure we're in that sweet spot. Justin: Awesome man, I know those colder plugs should definitely help with that detonation too. Mike J: Absolutely. Justin: Very cool, man. Well if you're all finished up, I want you to hop on out of there because I think it's my turn. I get to hop in, do another pull, and see what the numbers are. [engine noise] At the end of the Stage 1 Power Pack featuring our 2008 GT500, the car was making 508 horsepower and 479 pound feet of torque at the rear wheels. With all the Stage 2 modifications in the Power Pack installed, we were now putting down 548 horsepower and 545 pound feet of torque making for a gain of 40 horsepower over our Stage 1 numbers, and gains of 66 horsepower and 71 pound feet of torque throughout the curve. The Stage 2 Power Pack with pulley and supporting mods is always a favorite of GT500 owners, and I think it's pretty easy to see why. Honestly, there's nothing that compares to swapping those upper pulleys and really cranking up the boost. Hey, that's going to do it for the Stage 2 Power Pack Bolt-On Build-Up for all '07-'09 GT500's. Be sure to check out the other Power Packs for the GT500s and don't forget to subscribe to our YouTube channel if you haven't already. Thanks again for watching, and for everything Mustang, keep it right here at AmericanMuscle.com.

Regular Maintenance. Replacing your old weak spark plugs is paramount to keep your engine running smoothly and efficiently, so why replace them with the same old sub-par stock plugs when performance V-Power plugs from NGK will improve fuel efficiency and lower your emissions.

Superior Design. NGK V-Power Performance Spark Plugs feature a copper core for its superior conductivity and a durable nickel alloy tip to assure a strong spark to keep your stang running at it's peak efficiency. The V-Power plug features a unique V-Groove that allows the spark to happen at the edge of the center electrode, so that the heat is not absorbed by the electrode itself, resulting in a complete efficient burn.

Application. This set of eight (8) NGK V-Power Performance Spark Plugs are specifically designed as a direct fit replacement for the 2003-2004 SVT Cobra and the 2007-2014 Shelby GT500 Mustangs.

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

What's in the Box
  • (8) Spark Plugs
Installation Info
Tech Specs
Will it fit my Mustang?
  • Cobra - 03, 04
  • GT500 - 07, 08, 09, 10, 11, 12, 13, 14

People Who Bought This Item Also Bought

Most Helpful Reviews

5/5
Great product!

These plugs work fantastic on my 2007 Shelby GT500, I am very pleased!

Helpful (2)

5/5
NGK plugs

These plugs went in so easy haven't had any problems definitely recomend for 07-14 gt500

Helpful (2)

Overall Rating 4.8 out of 5 stars
Read All 26 Reviews

Customer Photos

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3 Questions / 3 Answers

Ask a Question

These spark plugs are listed in the 99 Mustang GT section. However, I do not see that they are meant to work with my year of Mustang. Are these still compatible with my 99 mustang?

BarringtonB

  • The NGK V-Power Spark Plugs will work with 2003-2004 Mustang Cobra's and 2007-2014 GT500's only and would not work with a 1999 Mustang. For your 1999 Mustang you would want to look at the version for your car, item number 64021.

    Rob D

Helpful (0)

What is the gap for these plugs? I checked several of them and they are at about .34 from NGK.

05GTHI

  • The NGK V-Power Spark Plugs, with the manufacturers part number TR6, stock number 4177 comes pre-gapped to .039"/1.0mm. You will still want to set gap on these prior to installation for your specific application.

    AMJEFF

Helpful (0)

Will these plugs work for a 2004 Mach 1 on 100 shot of nitrous? Are they cold enough, my car just has the basic CAI and exhaust. I want a good nitrous plug.

vityok

  • The NGK V-Power Spark Plugs - Heat Range 6 (03-04 Cobra; 07-14 GT500) are really designed to be just an upgraded factory replacement plug. I would not recommend these plugs for a nitrous setup. I would recommend a lower heat range spark plug.

    SalC7

Helpful (0)

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Customer Reviews (26) Write a Review

Overall Rating 4.8

out of 5 stars

Installation Time:Less than 1 Hour

  • Performance Gain 4.48 4.5
  • Fit 5 5



  • 5/5

    Installation Time: Less than 1 Hour

    April 19, 2017

    Great product!

    These plugs work fantastic on my 2007 Shelby GT500, I am very pleased!

    MSJR

    Year: 2007 Submodel: GT500

    Helpful (2)

  • 5/5

    Installation Time: Less than 1 Hour

    February 08, 2017

    NGK plugs

    These plugs went in so easy haven't had any problems definitely recomend for 07-14 gt500

    Whiteshelby

    Year: 2011 Submodel: GT500

    Helpful (2)

  • 5/5

    July 12, 2016

    Hot Plugs

    My 2013 GT500 Shelby Cobra had the original equipment spark plugs with 11,400 miles. I noticed the inside of the exhaust tips were too black, sign of running rich-too much fuel. So I opted for a set of NGK V-Power Plugs from American Muscle. I also installed a KandN Cold Air Intake and a JLT Oil Can on the passenger side to catch any oil before it slips into the supercharger. My GT500 runs way smoother and has better throttle response.

    Moe

    Year: 2013 Submodel: GT500

    Helpful (2)

  • 5/5

    Installation Time: Less than 1 Hour

    June 14, 2016

    Ngk heat range 6 v power spark plugs

    It took about a hour to install these and they perform excellent on my 2011 GT500 very happy with the results :)

    Shelby11

    Year: 2011 Submodel: GT500

    Helpful (2)

  • 5/5

    Installation Time: Less than 1 Hour

    September 18, 2015

    Good plugs for my stock 03 cobra

    I used the plugs as a tune up on my 03 cobra. install was easy and smoothed out the the idle a bit.

    Max

    Year: 2003 Submodel: Cobra Waynesboro PA.

    Helpful (2)

  • 4/5

    Installation Time: Less than 1 Hour

    November 23, 2014

    Adding boost get these

    I added a 10% pulley and a 2.6 pulley on my 08 gt500 (building over 15 psi of boost) and didn't change plugs. The car would lose power, misfire, and detention was taking place at WOT. Ordered these plugs, they showed up the next day. Install was easy just be sure the gap there correctly and add some anti-seize for good measure. The plug change fixed all the problems stated above. Great product and great delivery time

    JacobLane132

    Year: 2008 Submodel: GT500 Langley, Va

    Helpful (2)

  • 4/5

    Installation Time: Less than 1 Hour

    July 05, 2017

    Good plugs !

    Really the only spark plug I run with my cobra's , so I highly recommend these !

    97CobraSVT

    Year: 2003 Submodel: Cobra

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    July 02, 2017

    Great product for a good price

    My cobra was starting to miss hard during acralation. Bought these plugs that plugs because they were recommined on the forums and couldn't be happier. Fixed my issues and where much cheaper than other plugs out there.

    HoustonTull

    Year: 2003 Submodel: Cobra

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    April 26, 2017

    What a difference!

    I upgraded the pulley and went to a 2.5 so I went with a colder plug and let me tell you these plugs were super easy to install and these along with the other mods made a HUGE difference in performance. If you change your pulley and go smaller these plugs are the way to go!

    07beachGT

    Year: 2011 Submodel: GT500

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    March 08, 2017

    Plugs

    Direct replacement. Car runs smoother and better than factory.

    GreatOne

    Year: 1996 Submodel: Cobra

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    June 09, 2016

    Great Plugs for Procharged Mustangs

    I had autolites 3923 in my 1994 procharged 331 stroker Cobra. After purchasing MSD 6AL, Demon Screaming Coil, and Ford racing 9mm wires, I finally installed these plugs and I have smile on my face every time I take my Cobra out. Car idles much better, throttle response is awesome and most importantly during boost and over 4K RPM, my Cobra runs like BAT OUT OF HE11! My plugs are gapped at .030. Previously before getting MSD box and coil and wires, I was gapped at .025. If you have aluminum heads, don't forget the anti-seize. I completely forgot and pulled all the plugs out after installing them just to re-do. Do not neglect ignition parts if you are boosted. They do make a big difference in boosted cars.

    Ryan

    Year: 1994 Submodel: Cobra

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    September 18, 2015

    03 cobra back to life

    I bought these plugs for my terminator cobra because mine felt like they were going out, and they were bad, I changed them out in less than an hour and when i turned on the car and went around in it, I felt a huge power difference and it's crazy how much some plugs can do for your car. But these if you need new plugs they are great!

    Kris

    Year: 2003 Submodel: Cobra San Mateo California

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    May 22, 2015

    Great Plugs!

    Great plug to upgrade to when you are doing a tune up!

    AMCoalK

    Year: 2004 Submodel: Cobra

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    January 16, 2015

    Great product

    Works great, car runs a lot smoother. You can definitely tell a difference in the throttle response. Definitely regain a few horsepower.

    Sid03steeda

    Year: 2003 Submodel: GT Charlotte, NC, USA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    August 19, 2014

    Ngk is above the rest.

    I bought these plugs plugs for my tork tech powered gt. Gapping them were easy and we put them after we took off all the intake, rails, etc.

    FastEddie03GT

    Year: 2003 Submodel: GT Kentucky

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    May 27, 2014

    Sweet sparks

    Excellent replacement! I can feel it! Did a whole tune up and these sparks were the perfect product for my Terminator! Definitely recommend them!

    RedfireTermi

    Year: 2003 Submodel: Cobra Kailua, HI, USA

    Helpful (1)

  • 3/5

    October 17, 2017

    Half rating for half the supply!

    Seeing how I have only received four of the original 8 and still waiting for a month....even 3 is probably too high.

    PaulW

    Year: 2010 Submodel: GT500

    Helpful (0)

  • 5/5

    Installation Time: Less than 1 Hour

    October 16, 2017

    Great product

    Great plugs for my stock cobra! Will be using also for boltons!

    PaulC

    Year: 2003 Submodel: Cobra

    Helpful (0)

  • 5/5

    Installation Time: Less than 1 Hour

    April 14, 2017

    Big difference

    This is my second set of ngk tr6 plugs! I love them.

    Mike

    Year: 2003 Submodel: Cobra

    Helpful (0)

  • 4/5

    Installation Time: Less than 1 Hour

    March 31, 2017

    GT 500 Plugs

    Several things had to be moved, to be able to install the plugs. Plugs looked to be of good quality.

    Night500

    Year: 2008 Submodel: GT500

    Helpful (0)

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