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SR Performance Underdrive Pulleys (05-10 GT)

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Market Price $187.99 You Save 12% ($23.04)
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  • Item 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.

    SR Performance

    Fitment: 2005 2006 2007 2008 2009 2010 Details

    MPN# 41131

    CA Residents: WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov

    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?

      Customer Photos (44) Submit Your Photo

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        Questions & Answers (34)

        5 Top Rated Questions

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

        • 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.....

        Helpful (10) Show 2 more answers

        Does this require a tune?

        • The SR Performance Underdrive Pulleys do not require a computer tune.

        Helpful (7)

        Will the belt remain the same or does the belt have to be shorter or longer?

        • These pulleys allow you to reuse your factory belt.

        Helpful (2)

        Will this work on my 07 roush 427R supercharged Mustang?

        • These pulleys are compatible with the 2007 Roush 427R and will work with your Mustang.

        Helpful (2)

        can i use this for the Mustang 2006 V6??

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

        Helpful (1)
        Post Your Question
        10 More Questions
        Work with on a V6? I've seen on a few forums people were saying to increase HP on a V6 to get an underdrive pulley, but the only ones on here are for GT's. Was just wondering if these would work on a V6. 1 answer
        Will these give more power over the BBK or Steeda udp's? 1 answer
        Does this have a harmonic balancer? 1 answer
        Has anyone had difficulty in removing the crank bolt? I have used a breaker bar, it turns the engine over...I cannot seem to be able to wedge the pulley in place, or does it slide off with a 3-prong puller without needing to remove the bolt? Logic would require the crank bolt to be removed...but I lack upper body strength, and I even put the stock water pump pulley back on to use the belt for added stability. I am stuck. Any ideas would be great! I have the car in first gear, but my clutch is my next project...could the clutch issues be part of my problem or is there a way to wedge the pulley stable while I break the bolt loose? I don't want to use an impact wrench and screw up my timing! Help! Thanks in advance! 0 answer
        I have the SR 200 amp alternator because I have a large power drawing sound system as the stock alternator wasn't producing enough power. Will these underdrive pulleys cause decreased electrical power in my situation? 0 answer
        I bought the sr pulleys but i lost the crank bolt can i just installed it with the stock bolt or the sr bolt is required to use it .and do u sell the bolt separately . 0 answer
        I'm trying to install this product but the bolt for the crank shaft is not fully going in why is that? 1 answer
        wouldn't changing the water pump pulley make the car run hotter? because you are making the pulley bigger and the crank pulley smaller? 1 answer
        There's is a slight bend on my underdrive pulley. Like very very small on the lip. Is that going to effect anything to still use it? 1 answer
        Would this replace the stock pulley on a 2008 Crown Vic 4.6? 1 answer

          Customer Reviews (100+) Write a Review

          Overall Rating 4.7

          out of 5 stars

          Installation Time:Afternoon

          Installation Cost:$100-$250

          • Performance Gain 4.173554 4.2
          • Fit 4.778688 4.8



          • 5/5

            Installation Time: Afternoon

            July 09, 2019

            Good Quality

            Literally just installed them and can feel some gains

            AndresR

            Year: 2006 Submodel: GT

            Helpful (0)

          • 1/5

            Installation Time: Less than 1 Hour

            July 06, 2019

            Not worth it pure junk

            Installed it in February 2019 it's now July 2019 the outer ring where all the Allen bolts go in is mushroomed on the ring around each bolt and is loose pure junk

            Tjones128723

            Year: 2007 Submodel: GT

            Helpful (0)

          • 1/5

            Installation Time: Less than 1 Hour

            June 03, 2019

            Pulley install

            The front plate or damper on crank pulley rattled the screw loose tightend them and they rattled loose again and plate come off. Had to take pulleys off and wait til they sent me news ones so my car set til I got new ones in. After installing new ones the crank pulley is already raining after not being on long

            Jrl

            Year: 2007 Submodel: GT

            Helpful (0)

          • 1/5

            Installation Time: Less than 1 Hour

            May 23, 2019

            SR underdrive pulleys

            I Installed them and the same day they were making a funny noise like a bolt grinding no it wasn’t the alternator bolt come to find out after a few weeks of driving all the bolts are coming loose from the front of the crank pulley I tried to tighten them back up but does no good as the plate that gets bolted down Keeps free floating and rattling

            MichaelV

            Year: 2006 Submodel: GT

            Helpful (1)

          • 5/5

            Installation Time: Less than 1 Hour

            May 09, 2019

            Nice easy install

            In my case I put these on doing my motor swap. Nice simple quick install besides trimming the alternator bolts just a bit so the water pump pulley doesn’t have contact. With the bolt. Can definitely tell the difference with throttle response.

            ChristianL

            Year: 2006 Submodel: GT

            Helpful (0)

          • 5/5

            Installation Time: Afternoon

            April 26, 2019

            Decent

            Was a pretty easy install, Power gains are too noticeable. But they do look nice, engine did overheat once due to me forgetting to plug in the fan. Other than that no problems on the car.

            Manuel

            Year: 2005 Submodel: GT

            Helpful (0)

          • 5/5

            Installation Time: Afternoon

            April 25, 2019

            Sr performance pulleys

            The item is a underdog taken lightly mod in my opinion after doing cams full exhaust set up For tank years one piece driveshaft these pulleys complement everything, The car responds better As far as pedal to the metal if you know what I mean overall great product

            ArnoldA

            Year: 2005 Submodel: GT

            Helpful (0)

          • 5/5

            Installation Time: Less than 1 Hour

            April 24, 2019

            05-09 Mustang GT underdrive Pulleys upgrade

            Gain some what horse power not a lot. As per looks goes lots of Complements from friend and others who drive Mustang's

            RonC

            Year: 2006 Submodel: GT

            Helpful (0)

          • 3/5

            Installation Time: Less than 1 Hour

            April 19, 2019

            SR underdrive pulley.

            Installed this under and hour. Didn’t notice any house power but the car does rev up fast and the car does run a lot smooth and there is no drag. No over heating and I don’t use my a/c because my cams drain me my a/c but it does look very nice under the hood. Plus this was installed with the ford performance intake manifold.

            Somar

            Year: 2008 Submodel: GT

            Helpful (0)

          • 3/5

            Installation Time: Less than 1 Hour

            April 17, 2019

            Looks good

            Although these pulleys do look great, they do not add any hp or performance gains. Directions tell you to use a 3 prong puller to remove the crank pulley that is wrong. What you need is a wheel puller. There are 3 threaded holes in the pulley that you insert the puller into to remove the crank pulley. Other then that they look great but as far as performance gains there are none.

            05GT

            Year: 2005 Submodel: GT

            Helpful (0)

          • 5/5

            Installation Time: Afternoon

            April 01, 2019

            SR Performance Underdrive Pulleys

            Haven't seen or felt a hp increase but it's seems like I'm getting better gas mileage. And they look good on the engine.

            MichaelD

            Year: 2007 Submodel: GT

            Helpful (1)

          • 5/5

            Installation Time: Afternoon

            April 01, 2019

            SR Underdrive Pulleys

            I installed these in my wife’s 06 GT automatic and it feels like it has no strain on the motor now plus they look great I recommend.

            HalH

            Year: 2006 Submodel: GT

            Helpful (0)

          • 1/5

            Installation Time: Shop Install

            Installation Cost: $500-$1000

            March 31, 2019

            Don't do it !

            I put this on my 06 mustang gt and it overheated badly and almost blew my motor. They should tell you in there video you will need other mods for this to worked. Never buying from you again!

            LesterS

            Year: 2006 Submodel: GT

            Helpful (2)

          • 5/5

            Installation Time: Afternoon

            March 26, 2019

            SR underdrive pulleys

            Pretty easy install only a couple hours, you can feel a bit more power in the mid range and there is no difference in accessories.

            AnthonyC

            Year: 2010 Submodel: GT

            Helpful (0)

          • 5/5

            Installation Time: Shop Install

            Installation Cost: $100-$250

            March 18, 2019

            A must buy

            Love this product not hard to install looks good and you can realy tell the difference you must buy price is write

            LonD

            Year: 2005 Submodel: GT

            Helpful (0)

          • 5/5

            March 13, 2019

            Longevity review

            I've had the SR performance Underdrive pullies on my car for aver 3 yrs now, when i first got the kit it was nice and shiny, almost looked to good to put on my car, after it was on my car for about a month, i noticed the balance started to get some surface rust on it, i took some scotchbrite and tried to remove the rust in doing so, the timing marks on the balance were removed, no big deal, until i installed my FRPP hot rod cams this weekend and i needed to see the marks, and of course with no marks it made the cam install a little more difficult... if you buy this kit just make sure you mark where the timing marks are and some clear coat wouldn't hurt either, all in all these pulleys do work, i picked up 11 rwhp on the dyno, the engine rev's fast and they have lasted this long, no since in paying more for the same name brand, no issues with my charging system or accessories ! great bang for your buck

            KeithD

            Year: 2008 Submodel: GT

            Helpful (4)

          • 5/5

            Installation Time: Afternoon

            March 12, 2019

            Underdrive Pulleys

            Bought these for son's Mustang. I have similar pulleys on my car and could tell a difference as soon as I installed them. No problems with battery charging, work great and installed in about 2 hours.

            Mort

            Year: 2007 Submodel: GT

            Helpful (0)

          • 5/5

            Installation Time: Less than 1 Hour

            March 07, 2019

            Great for the price

            Pulley and sprint booster give me car another identity

            FlameKeeper

            Year: 2008 Submodel: GT

            Helpful (1)

          • 5/5

            Installation Time: Shop Install

            Installation Cost: $100-$250

            March 01, 2019

            Power

            Well built, looks good, light, good upgrade for little money.

            JamesD

            Year: 2008 Submodel: GT

            Helpful (0)

          • 5/5

            Installation Time: Afternoon

            February 19, 2019

            Awesome underdrive pulleys

            It was easy to install. Slide right on. Stang running strong

            MartellC

            Year: 2009 Submodel: GT

            Helpful (0)

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