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SR Performance Underdrive Pulleys (05-10 GT)

Market Price $186.99 You Save 12% ($22.04)
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$164.95

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  • Item 41131
  • MPN# 41131

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Features, Video & Details

  • Free Up Horsepower
  • Complete Kit
  • Durable, Lightweight Aluminum
  • Brilliant Polished Finish
  • Premium Quality
  • Fits 2005-2010 GT and Bullitt Mustangs

Review & Installation Video

Review & Install Video

Hey I’m Justin with AmericanMuscle.com, and I’m breaking down these underdrive pulleys from SR Performance, fitting the 4.6L V8 motor found in all 2005-2010 Mustang GTs. Engine accessories like the AC compressor, water pump and alternator can really rob your car of horsepower, a great example of how much power an accessory can eat up is whenever you turn your cars AC on and instantly it feels a little more sluggish. This is referred to as parasitic drag. The idea of an underdrive pulley is to turn the different accessory pulleys at a different speed, using these different sized pulleys thus requiring less power from the motor to drive each accessory. This reduction in drag on the crank shaft should allow the motor to operate more efficiently, and essentially equate to more power at the rear wheels. The SR Performance kit includes a new water pump pulley along with a brand new crank pulley, and the hardware needed for the install. Both pulleys are SF5 certified and are constructed using lightweight aluminum. As an added bonus, that bright polished finish is sure to look good under the hood as well. As far as the install is concerned, you just want to leave yourself a couple of hours to get both pulleys installed. Ideally, you should have a torque wrench on hand as well as some high temp RTV sealant and a breaker bar for that crank pulley bolt. This isn’t the hardest job in the world, but if you’ve never attempted it before, I really suggest watching the detailed instruction video located on this product page before getting started on the install. So be sure to check out the SR Performance underdrive pulleys right here at AmericanMuscle.com

Untap Hidden Horsepower. Don't let your accessories and A/C drain power from your GT or Bullitt Mustang. By replacing your factory pulleys with this SR Performance Underdrive Pulley Kit, you'll free up to 15 horsepower that's currently being drained by your accessories and put it back where it belongs - under your right foot. Best of all, you won't affect your vehicle's charging or cooling capacity in the process.

SFI Certified Design. If you're ready to take it to a track, you'll rest easy knowing these SR Performance Pulleys are SFI Certified.

Premium Quality. Don't settle for inferior parts. These premium quality SR Performance Pulleys are made from lightweight aluminum for durability and performance. Made using precise, state-of-the-art CNC manufacturing, you can count on these pulleys to perform at the highest level.

Easy Installation. This SR Performance Mustang Underdrive Pulley Kit installs quickly and easily in under 2 hours with no modifications required.

Application. These SR Performance Underdrive Pulleys are specifically designed for use on the 2005 to 2010 GT and 2008 to 2009 Bullitt Mustangs.

Fitment: 2005 2006 2007 2008 2009 2010 Details

What's in the Box
  • (1) Crank Pulley
  • (1) Water Pump Pulley
  • (1) Crank Bolt
  • (1) Instruction Sheet
Installation Info
Tech Specs
Underdrive Pulley Specifications
Year/Model: 2005-2010 GT Manufacturer: SR Performance
Material: Aluminum Finish: Polished
Crank Pulley: One Piece Crank SFI Certified: Yes
Will it fit my Mustang?
  • Bullitt - 08, 09
  • GT - 05, 06, 07, 08, 09, 10

People Who Bought This Item Also Bought

Most Helpful Reviews

5/5
SR Underdrive Pulleys added low end power

I installed the pulleys in about 2 hours. The additional pull from 1500 to 3500 rpm was noticeable, higher rpm not as noticeable. Worth the cost and effort.

Helpful (1)

5/5
Can't beat it for the price!

I decide to go with the SR. because it was getting great reviews. I am happy I did, the fit was perfect and the gains were noticeable. I would recommend buying a new bolt ( m8 1.25 x 2" ) instead of cutting ...

Read More
Helpful (1)

Overall Rating 4.7 out of 5 stars
Read All 69 Reviews

Customer Photos (32) Submit Your Photo

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14 Questions / 7 Answers

Ask a Question

Low accessories power? How much power will this take away from the accessories? Is it a noticable difference or not?

Josh08

  • I had the same worries, but after the install I checked the output voltage on the alternator and all around the vehicle before and after the installation and there was no power shortage at all, and for the performance the pony revs way more faster......and it looks cool.....

    Rafael

Show 2 more answers Helpful (6)

What's the diameter of the crank pulley?

ET

can i use this for the Mustang 2006 V6??

Jose

  • These pulleys will not work for the 2006 V6 Mustangs.

    KevinD92

Helpful (0)

How much will power steering be reduced? I understand it will lose a bit but like. How bad. If my steering is gonna be hard at low speeds then i wonder if its worth the extra horses. Let me know any downsides anyone notices. Thanks!

JacobH

  • Hello! You should not notice much of any difference from the SR Performance Underdrive Pulleys in terms of power steering. The pulleys focus more on accessories and a/c

    JacobC

Helpful (0)

What accessory does this replace? Does it replace the a/c?

Anonymous

  • These SR Performance Underdrive Pulleys replace the crank pulley, and the water pump pulley.

    AMJEFF

Helpful (0)

Hi, i have installed the pulley today and have a little question : is it normal than the steering is really harder ? I think it's due to the pulley reduction but can someone confirm that ? (i hope, if not i have a steering prob)

Nico

  • It is normal, this is due to the power steering pump being spun slower than normal.

    AMSam

Helpful (0)

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Customer Reviews (69) Write a Review

Overall Rating 4.7

out of 5 stars

Installation Time:Afternoon

Installation Cost:0-$100

  • Performance Gain 4.225806 4.2
  • Fit 4.809524 4.8



  • 5/5

    Installation Time: Afternoon

    October 30, 2016

    SR Underdrive Pulleys added low end power

    I installed the pulleys in about 2 hours. The additional pull from 1500 to 3500 rpm was noticeable, higher rpm not as noticeable. Worth the cost and effort.

    Bob

    Year: 2008 Submodel: Bullitt

    Helpful (1)

  • 3/5

    October 10, 2016

    Worth the change?

    While the parts look good and the install was exactly as expected, the performance gain is very small. .03 of a second in the quarter isn't much of a gain. Just need to get more aggressive with my parts upgrades.

    STMPEAD07

    Year: 2007 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    September 15, 2015

    Can't beat it for the price!

    I decide to go with the SR. because it was getting great reviews. I am happy I did, the fit was perfect and the gains were noticeable. I would recommend buying a new bolt ( m8 1.25 x 2" ) instead of cutting the factory one. I needed an impact gun because you can't get enough fast rotational torque with a breaker bar. It was a straight forward install just follow the guide. I would recommend these pulleys

    Danger

    Year: 2007 Submodel: GT Palm Coast, Florida

    Helpful (1)

  • 5/5

    Installation Time: Full Day

    December 19, 2014

    Awesome

    The review title says it all these under drive pulleys are great I am very happy with this purchase they look great I prob could have had it done in an afternoon but I wasent in a rush and took my time making sure I had the pulley puller and followed all steps I did have an issue with the crank turning while in first gear and trying to remove the old crank pulley but it was an easy fix I just used a rubber adjustable filter wrench to hold the pulley in place so I could remove the bolt it took me about five mins to get the bolt out this way as my impact gun would not break it free

    BOuT05GT

    Year: 2005 Submodel: GT Gainesville, GA, USA

    Helpful (1)

  • 5/5

    Installation Time: Shop Install

    October 11, 2013

    underdrive pulleys

    For the money you can't beat this product. Only problem was the motor would not stop turning. Had to wedge a piece of wood between pulleys to stop turning than it was a piece of cake. Looks great but not sure what I gained as I have not yet re-dynoed my car. 353 rwhp before install.

    jitz47

    Year: 2008 Submodel: GT Chatham, NJ, USA

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    July 10, 2013

    AC on No Problem

    The pulleys are an excellent product! I decided to purchase the pulleys when I noticed a drop in power with the AC turned. It made the car feel a bit sluggish. The under drive pulleys restored the lost power lost with the AC turned on. Now I can enjoy the hot summer days in my mustang with the AC on and not feel the sluggishness when I want to put my foot into it. The pulleys look good and the construction of them is solid. The pulleys were easy to install with the instructions on American Muscle's website.

    TorchRed06

    Year: 2006 Submodel: GT Guymon, OK 73942, USA

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    June 19, 2013

    SR Underdrive Pulleys

    These are a great bang for your buck. They do make a noticeable difference in performance with no side effects, a/c is still ice cold, no overheating, etc. They also install easy in a few hours provided you use air tools. Just cut the stud on the alternator for clearance and get a new crank bolt from ford, its so cheap might as well. Overall I'm very satisfied with this mod. Also if you have an automatic like me, remove the flex plate cover and hold a bolt on it instead of on the torque converter.

    MarkL

    Year: 2006 Submodel: GT Fair Haven, NJ

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    November 15, 2012

    Hit

    pulling accessories causes a lag and robs horse power and man does this give it back, its not a bang for your buck its a hit, hit the gas and you will feel all the go for your doe. I love it. Troy

    Troy469

    Year: 2006 Submodel: GT roanoke rapids nc

    Helpful (2)

  • 5/5

    Installation Time: Afternoon

    April 03, 2012

    Great Bang for Your Buck

    The pulleys look good,installation was a piece of cake,the only recomendation for the install is to get a M8-1.25x2 bolt to replace the alt stud,instead of cutting the stud for the waterpump pulley to clear. Noticed a slight power gain. Great product for the price.

    drmustang

    Year: 2006 Submodel: GT N. Myrtle Beach SC

    Helpful (8)

  • 5/5

    Installation Time: Afternoon

    February 27, 2012

    Horsepower Increase

    Awesome Product just as good BBK, without all the price. Just buy a new bolt instaed of cutting the one on your vehicle. Take your time, snap a picture of how your belt diagram, just in case.

    IndigoBlue

    Year: 2008 Submodel: GT Agoura Hills, CA

    Helpful (6)

  • 5/5

    Installation Time: Afternoon

    January 27, 2012

    Fuel Millage

    The day after the install of the new pulleys, I took the car for a trip. I got 26- 28 mpg! I have never seen that before, so it clearly made a difference. I have since done a few more bolt-ons and together they have turned the car into a real handful! When I speed shift into second, hold on becouse she is going to pull sideways and then bark a hard 3rd! The pulleys were easy to install. I have already recommended that my friends to do the same. Cannot wait until the track opens to see the new times. Fastest pass has been 13.7 totally stock.

    supercross

    Year: 2010 Submodel: GT Anderson Texas

    Helpful (9)

  • 5/5

    Installation Time: Afternoon

    February 23, 2012

    Pulley = Epic Win

    Hardest part about getting these installed was finding a friend with all the parts. It was a helluva lot of fun putting these on, the instructions were right on point. Note: this WILL require removing some hoses so you will want to be aware of some possible dripping. I'd have to say the car is a bit more peppy, I'm able to do wonderful things in 1st gear with no gas... Great fun!

    AustinJim

    Year: 2008 Submodel: GT Austin, Tx

    Helpful (3)

  • 3/5

    Installation Time: Less than 1 Hour

    March 05, 2012

    Price wise, better then other pulleys, power is ok

    I work at Mustang Specialties, I purchase this set for my personal 09 GT did a before and after dyno. made 316rwhp before the install. Install went smooth and everything fit no problem and looks great. went ahead and dyno'd the car after the install same day just an hour later. car made 320rwhp with the pulley install. So with no other changes at all on the car what so ever this car will give a dyno proven 4rwhp. For me its not worth it, the car on nitrous still ran the same time and mph 11.5X@118-119

    KOTSCHRIS

    Year: 2009 Submodel: GT

    Helpful (9)

  • 4/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    September 26, 2013

    Smooths out performance a bit, but don't expect miracles

    I recently had these UD pulleys installed alongside a set of FRPP 3.73 gears. They seem to have offset the slight (1-2 mpg) drop expected by jumping from 3.31 to 3.73 rear end, and overall the car feels like it runs a little smoother. The engine feels as though it revs a little freer as well. Install cost for the pulleys was $75. A solid mod and I would buy them again.

    TitanJC

    Year: 2007 Submodel: GT The Woodlands, TX

    Helpful (2)

  • 5/5

    Installation Time: Less than 1 Hour

    June 29, 2012

    SR Performance Underdrive Pulleys (05-10 GT)

    This was a simple install about 1+ hours to do, It looks great and there is a very noticable HP gain.

    BobD

    Year: 2008 Submodel: GT Selinsgrove, PA.

    Helpful (2)

  • 3/5

    Installation Time: Less than 1 Hour

    December 01, 2011

    Great just a few things to watch out for..

    Pros- great power gain and is identical to the BBK pulleys..pretty easy install Cons- the bolt that is provided needs to be shorter or a has to have a spacer... (the bolt as is will run out of threads leave the crank pulley only half pressed on).. by adding a washer it allows the bolt to pull in the pulley more.... Other thing is I have to switch to a smaller serpentine belt because my tensioner was maxed out and was causing the belt to slip...

    DaminB

    Year: 2007 Submodel: GT OC

    Helpful (8)

  • 4/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    May 18, 2012

    Power when you want with fuel savings

    The stang definitely feels quicker on it's feet and the lighter pulleys help deliver better gas mileage when you're not gunning it. Best of both worlds. I got this installed at a shop, total labor cost $190 for a 2 hour job but it was worth it because they had to shave off a certain stud because one of the pulleys sits too deep. I think this is a great bang for your buck. With increased gas mileage, the pulley will pay for itself in about 2 years. Not bad.

    Nitin

    Year: 2005 Submodel: GT Fremont, CA

    Helpful (2)

  • 5/5

    Installation Time: Afternoon

    March 08, 2012

    The best!

    I installed these on my 08 Shelby GT CS. It took about 2 hours and the results are amazing! They look great and install perfectly. I was so amazed at the horsepower, torque, and throttle response these achieved. If it wasn't for my racing lower control arms, it would be hard to keep traction on the road! I highly recommend!

    Tdavis

    Year: 2008 Submodel: GT Longview, Texas

    Helpful (2)

  • 5/5

    Installation Time: Less than 1 Hour

    May 08, 2012

    Perfect Pulleys

    I was a bit apprehensive going with the cheaper Stack Racing brand pulleys but couldn't be happier with this bolt on. Very easy installation that can be completed easily under an hour.

    6806mustang

    Year: 2006 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    February 29, 2012

    eye candy

    made the engine look better, a slight notice in power and only took about 1/2 hour to install.

    camaros68

    Year: 2006 Submodel: GT zanesville, ohio

    Helpful (1)

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