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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

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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

    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?

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    Questions & Answers (31)

    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 (6)

    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
    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? 0 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? 0 answer
    Would this replace the stock pulley on a 2008 Crown Vic 4.6? 1 answer
    How long after getting everything put back together should I wait before starting or driving my car? 1 answer
    What kind of horsepower gain can you expect with these pulleys 1 answer
    Can this install require a new tune update and will that add any additional gains? Compared to just an install without a retune? 1 answer

    Recommended For You

    Customer Reviews (100+) Write a Review

    Overall Rating 4.7

    out of 5 stars

    Installation Time:Afternoon

    Installation Cost:$100-$250

    • Performance Gain 4.212389 4.2
    • Fit 4.833333 4.8



    • 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 (0)

    • 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 (3)

    • 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)

    • 5/5

      February 12, 2019

      Great

      Easy to order...no problems . Very simple. They everything you need for your vehicle

      SheltonG

      Year: 2006 Submodel: GT

      Helpful (0)

    • 5/5

      Installation Time: Less than 1 Hour

      January 27, 2019

      Love it

      Simple easy way to get a little more horses out of my pony, felt the instant gain. Make sure you have all the right tools and it'll take about 30 to 45 minutes to install

      Carlos

      Year: 2006 Submodel: GT

      Helpful (0)

    • 5/5

      December 30, 2018

      Nice for the price

      They look great under the hood, noticed a difference seemed a little more responsive. I would buy them again, you will need a 3 prong puller which a lot of people suggest the Chrysler puller fortunately my dad is a mopar guy so I used his. Also a cut of wheel if you don’t buy a different bolt for the alternator. I took my time installing finished 1 1/2 hr.

      ThomasT

      Year: 2007 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      December 04, 2018

      Horsepower Reallocation

      Well written instructions. Easy enough to install.I think if I never think about it again it will be a success. You need a gear puller.

      BradleyR

      Year: 2008 Submodel: GT

      Helpful (1)

    • 5/5

      December 03, 2018

      Very good quality

      Look good and fit good, especially for the price. Cant tell much of a gain. Also after install, ive never had a problem with it under driving the alternator like some people say.

      LoganH

      Year: 2007 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Afternoon

      November 13, 2018

      Pulleys

      These are definitely worth it! I could definitely feel a difference in pull. And it gave my car a slightly lower exhaust note. My only advice is if you don’t have an impact gun of some kind then get one, or let someone else do this for you.

      B

      Year: 2006 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Afternoon

      September 11, 2018

      Physics Is On Your Side!

      These pullies work great. You definitely feel some type of power gains from it. Of course they claim it adds an extra 10 horse power and have dyno charts to prove it. Definitely felt the torque. I recommend SR to maybe add an extra instructions on where to find the certain tools. I went to autozone to rent a 3 prong pulley puller. It was a universal and even that did not fit to help on the mustang. It was a real hassle getting that crankshaft pulley off. Definitely recommend a professional to help out in a situation like that since you are messing with your engine in a situation like that.

      RemiB

      Year: 2009 Submodel: GT

      Helpful (4)

    • 5/5

      Installation Time: Afternoon

      August 14, 2018

      PULLeys

      I felt a little extra pull!! Install was decent. Got installation for $200.

      GabeL

      Year: 2008 Submodel: GT

      Helpful (2)

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