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SR Performance Underdrive Pulleys (Late 01-04 GT)

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Market Price $108.99 You Save 13% ($14.00)
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$94.99

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  • Item 388722

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    Features, Video & Details

    • Gain Horsepower
    • Complete Kit
    • Durable, Lightweight Aluminum
    • Brilliant Polished Finish
    • Premium Quality
    • Fits Late 2001 to 2004 GT

    Review & Installation Video

    Review & Install Video

    Hey I’m Justin with AmericanMuscle.com, and I’m going to be breaking down the SR Performance underdrive pulleys, fitting the 4.6L V8 motor found in all 96-04 Mustangs. Engine accessories like the AC compressor, water pump and alternator can really rob your car of horsepower, a great example of how an accessory can really eat up is whenever you turn your car’s AC on, and instantly everything feels a little more sluggish. This is referred to as parasitic drag. The job of an underdrive pulley is to turn the different accessories at a different speed by using a different sized pulley, thus requiring less amount of energy from the engine to turn the accessory belt. This reduction in drag on the crank shaft will allow the engine to work more efficiently, and should equate to more power at the rear wheels. The SR Performance kit does include a brand new crank pulley, a new water pump pulley which will differ depending on your year, a new alternator pulley, and all the hardware and spacers needed for the install. All 3 pulleys have been made from lightweight aluminum and feature a nice bright polished finish, which should definitely help the appearance side of things underneath the hood. As far as the install is concerned, it really shouldn’t be all that bad, ideally, you should have a torque wrench on hand before you get started, as well as some high temp RTV sealant and a breaker bar for that crank pulley. Again this isn’t the hardest job, but you should expect to spend about 2 hours getting everything bolted up. If you should have any problems, you can always reference the detailed instructions along with pictures located on this product page. So if you’re looking to take some of the drag off your accessories, in turn freeing up some horsepower, and improving your throttle response, then you should definitely check out these pulleys from SR Performance, available right here at AmericanMuscle.com

    Untap Hidden Horsepower. Add some more bite to your GT's bark by reducing the amount of power you're losing to accessories and A/C. When you install this underdrive pulley kit, you'll free up up to 15 horsepower - and it's pretty much all gain and no pain, since you won't sacrifice your charging characteristics or A/C to do it.

    Premium Quality. Don't settle for inferior parts. These premium quality 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 Underdrive Pulley kit installs quickly and easily in under 2 hours with no modifications required.

    Application. These underdrive pullies are designed for the Late 2001 to 2004 GT with the short water pump pulley with a bowed in face. Re-uses factory serpentine belt.

    Technical Note. Midway through the production run for the 2001 model year Ford changed the design of the water pump on the 4.6L engine. The older style pump produced from 1996 to mid 2001 had a longer shaft. In January of 2001 the design of the pump was changed to a shorter shaft. This necessitated a change in the design of the pump pulley.

    Click here to see pictures of the different pulley styles.

    Fitment: 2001 2002 2003 2004 Details

    MPN# 388722

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

    What's in the Box
    • (1) Crank Pully
    • (1) Water Pump Pully
    • (1) Alternator Pully
    • (2) Spacers
      Hardware included:
    • (4) Bolts
    • (3) Washers
    • (1) Crank Key
    Installation Info
    Tech Specs
    Underdrive Pulley Specifications
    Year/Model: Late 01-04 GT Manufacturer:
    Material: Aluminum Finish: Polished
    Crank Pulley: Piggyback SFI Certified: No
    Will it fit my Mustang?

      Customer Photos (7) Submit Your Photo

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        Questions & Answers (7)

        5 Top Rated Questions

        Do these piggyback on the harmonic pulley?

        • Thank you for your question about the SR Performance Underdrive Pulleys (Late 01-04 GT). The crank pulley does piggyback on the harmonic balancer pulley.

        Helpful (1)

        When will AM have 99-04 V6 mustang underdrive pulleys? I would like a set, but the only set is $350 from some sketchy website.

        • We are constantly getting new products on our site, so keep checking back!

        Helpful (1)

        How exactly does this make you gain horsepower and speed. And if I'm running a 1/4 mile at 97.68 will this push me over 100mph if I also switch from a 91 tune to a 93.

        • This reduced the amount of power lost from the AC and other accessories resulting in power gains.

        Helpful (0)

        Hey, I need to know the dimensions of the alternator pulley I have this kit on my car but alter was changed at a shop and I believe the pulley did not get swapped over to the new alternator.

        How are the spacers used exactly?

        • The2 included spacers are used to align the alternator pulley with the rest of the pulleys.

        Helpful (0)
        Post Your Question
        2 More Questions
        Wil these pullies be ok with stage 2 cams? 1 answer
        how much does this kit change change the ratio at the crank? What is the diameter of the stock crank pulley and what is the diameter of the BBK? Thanks. 1 answer

          Customer Reviews (37) Write a Review

          Overall Rating 4.2

          out of 5 stars

          Installation Time:Afternoon

          Installation Cost:$100-$250

          • Performance Gain 4.225806 4.2
          • Fit 4.258065 4.3



          • 5/5

            Installation Time: Afternoon

            May 06, 2019

            Real results

            Gained about a tenth to two tenths of a second in a quarter mile. Good quality easy to install if you have the right tools. I would definitely recommend this product.

            NHRAbatmobile52

            Year: 2004 Submodel: GT

            Helpful (0)

          • 1/5

            Installation Time: Less than 1 Hour

            February 06, 2019

            do not recomend

            pulleys feel cheap and are waterpump spins too slow causing higher temps and at idle you are running off your battery.

            DavidF

            Year: 2003 Submodel: GT

            Helpful (0)

          • 5/5

            Installation Time: Afternoon

            October 24, 2018

            Amazing!

            Great product and yet super affordable! It took a few hours but it was worth the time sure does make a difference in your cars performance.

            CesarB

            Year: 2001 Submodel: GT

            Helpful (1)

          • 5/5

            Installation Time: Less than 1 Hour

            September 01, 2018

            perfect!

            worth the price felt a slight diffrence with a nice look when you pop the hood!

            BrianB

            Year: 2004 Submodel: GT

            Helpful (1)

          • 2/5

            August 13, 2018

            Good kit for the price. BUT..

            It looks clean under the hood, I liked the kit... but, one of the bolts holding the crank pulley and balancer together completely snapped at 12 Ft. IB of torque. I installed the kit, then drove the car, then re-torqued (which they were slightly loose) then drove it again, and went to re-torque again today. One just kept spinning and....... snap. Not really sure what i'm gonna do.

            AndrewR

            Year: 2004 Submodel: GT

            Helpful (1)

          • 5/5

            Installation Time: Less than 1 Hour

            July 20, 2018

            under drive is the is great

            these pulleys are fantastic...the engine runs so smoothly. best bang for the buck...get some on your car...

            PhillipR

            Year: 2001 Submodel: GT

            Helpful (3)

          • 3/5

            Installation Time: Less than 1 Hour

            May 25, 2018

            Nice

            They look great do great. I think you should let it be known the harmonic balancer is a piggyback on the crank.i also wonder how it affects the crank bearing number 1? But with my tune from AM and these O yea we fly

            Fordman

            Year: 2003 Submodel: GT

            Helpful (3)

          • 5/5

            Installation Time: Less than 1 Hour

            May 10, 2018

            Must Buy BoltOn

            Very cheap bolt on that really makes a difference and definitely worth every dollar!

            AntonioM

            Year: 2003 Submodel: GT

            Helpful (3)

          • 5/5

            Installation Time: Less than 1 Hour

            April 16, 2018

            Wow

            Great looking 2003 mustang..make the engine look great

            JamesP

            Year: 2003 Submodel: GT

            Helpful (3)

          • 5/5

            April 08, 2018

            loved this

            This cat was very easy to install expect to use a harmonic balance puller Other than that it was very straightforward install

            JonathanH

            Year: 2003 Submodel: GT

            Helpful (3)

          • 5/5

            Installation Time: Afternoon

            January 20, 2018

            Underdrive Pulleys

            Easy install, great look under the hood and noticeable gain on throttle. I would recommend to anyone looking for mods on a budget.

            ChrisYoungblood

            Year: 2003 Submodel: GT

            Helpful (4)

          • 5/5

            Installation Time: Less than 1 Hour

            December 25, 2017

            Mustang

            Great little mod to gain just a little more power!

            Matthew

            Year: 2002 Submodel: GT

            Helpful (5)

          • 5/5

            Installation Time: Afternoon

            October 20, 2017

            My favorite mod

            Install was fairly easy, but I was bummed that I had to keep the old crank pulley attached to the new one. It would be nice to have less rotational mass. I got noticeable acceleration gains immediately from low rpm all the way up. This is an excellent mod and power increase for the money. The only problem I experienced years later was a little belt slippage and squeaking but that stopped after I put rubber conditioner on the belt.

            Chasing300

            Year: 2001 Submodel: GT

            Helpful (4)

          • 4/5

            Installation Time: Weekend

            October 13, 2017

            As Advertised

            Like always product came quickly and in good shape. Directions were good. Unfortunately removing a drive pulley that is 14 years old is not for the feint of heart. I struggled with the bolt for two days and 10 you tube videos later, success. Of course it was impossible without a pulley puller which I am very glad I purchased in advance. My impact wrench was useless unless I wanted to remove yet more "stuck" parts. I am satisfied with the performance and the annoying screeching of the alternator bearing is no more. I would recommend this product. Again; make sure you have the tools and patience as it is a must have during this project.

            MatthewW

            Year: 2003 Submodel: GT

            Helpful (4)

          • 4/5

            Installation Time: Full Day

            September 15, 2017

            Good product, the crank pulley is a tad tricky

            I've posted this same review on most other bolt-on products... It is well made and comes with what you need to install. I believe I put the brass spacer between the pulley and alternator. I bought all the typical bolt on stuff from SR Performance, (75 mm throttle body, plenum, spacer, CAI, UD Pulleys, etc...) and FRPP 4.10 gears. The car felt much better than stock! I recently took everything off for California SMOG, except the gears and hardly noticed any difference. I'm not going to bother reinstalling anything as I should have just listened to what EVERYONE else said and buy a blower... So I have a Kenne Bell ready to go on soon that IS California legal and will actually show massive gains. Not to knock SR Performance or any other company, but the bolt-ons just are not worth it. Save the money up for FI if you really want some power. AND DEFINITELY GET 3.73 OR 4.10 GEARS!!!

            Gezus

            Year: 2004 Submodel: GT

            Helpful (6)

          • 5/5

            Installation Time: Afternoon

            September 04, 2017

            Sr performance pulleys

            Fast shipping, good quality product, installation not to difficult, big performance improvement. Would strongly recommend these pulleys for that little bit of an edge in horse power gain.

            EdwardM

            Year: 2002 Submodel: GT

            Helpful (3)

          • 2/5

            Installation Time: Less than 1 Hour

            June 16, 2017

            shiny pulleys

            they are fine pulleys and look great but i wasn't happy with the piggy back style of the damper.

            sicsytec

            Year: 2003 Submodel: GT

            Helpful (4)

          • 5/5

            February 23, 2017

            Niiice

            They're pretty cool haven't found anyone to put them on yet. I'm glad I don't need a new belt.

            DESIII

            Year: 2000 Submodel: GT

            Helpful (5)

          • 5/5

            Installation Time: Less than 1 Hour

            February 18, 2017

            Awesome

            They installed easy look great added these and a kandn air intake and way more power and gas mileage

            KoryF

            Year: 2003 Submodel: GT

            Helpful (7)

          • 4/5

            Installation Time: Less than 1 Hour

            February 06, 2017

            Good product

            Nice look under the hood slight gains good bang for your buck

            JonathanP

            Year: 2003 Submodel: GT

            Helpful (6)

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