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Steeda Underdrive Pulleys (Late 01-04 GT)

Market Price $268.99 You Save 11% ($29.04)
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  • Item 16090
  • MPN# 701-0003

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Features & Details

  • SFI Approved
  • 8 - 10 RWHP Recovery
  • Improves Fuel Economy
  • 25% Reduction in Parasitic Accessory Drag
  • Exceeds OEM Material Specifications
  • Fits Late 2001 to 2004 GT Mustangs
Regain Lost Power. Get back the power and torque your belt-driven accessories steal. As hard as it may be to believe, you can regain from 8 to 10 “free” horsepower with Steeda’s underdrive pulleys. These pulleys reduce engine parasitic drag from your accessories by about 25% and even improve fuel economy.

Superior Materials. Steeda underdrive pulleys are manufactured from nodular iron, and far exceed the quality of the factory pulleys. The one-piece crankshaft pulley uses a high-tech injection molded bonded rubber damper, making it far more durable than other manufactures "piggyback style" underdrive pulleys.

SFI Approved. Steeda underdrive pulleys are SFI approved for use by all major race sanctioning bodies.

Application. These Steeda Underdrive Pulleys are specifically designed for use on the Late 2001 to 2004 4.6L V8 GT Mustangs.Re-uses factory serpentine belt.

Note: Coupon codes cannot be applied to this product.

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

What's in the Box
Hardware included:
  • Crankshaft pulley
  • Water pump pulley
  • Alternator pulley
  • Crankshaft pulley starter bolt*
* must be removed after seating pulley!
Installation Info
Tech Specs
UnderDrive Pulley Specifications
Year/Model: Late 01-04 GT Manufacture: Steeda
Material: Steel Finish: Black
Crank Pulley: One Piece Crank SFI Certifited: Yes
Will it fit my Mustang?
  • GT - 01, 02, 03, 04

Fits Mid 2001 to 2004 GT's Only

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Most Helpful Reviews

Steeda Underdrive Pulleys

I have a highly modified 4.6L two valve drag car, that I also keep legal for the street. Because of my speed in the quarter mile I must use SFI rated parts for safety. Steeda parts, are always of the highest ...

Read More
Helpful (1)


Getting the old pulleys off was a bit of a pain, especially the dampener. Putting them on was easier than expected and took about an hour-hour and half taking my time, cleaning things as I went. Felt ...

Read More
Helpful (2)

Overall Rating 4.7 out of 5 stars
Read All 78 Reviews

Customer Photos (11) Submit Your Photo

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8 Questions / 9 Answers

Ask a Question

Do I need to buy a more powerful alternator when fitting these pulley's as some of the comments suggest? I recently bought a remanufactured stock alternator and I want to know if that is good enough for this pulley.


  • They will work great if you don't have a big sound system. The only time they will show a low charge is at idle,But if your alternator is working properly you will not have a problem.


Show 4 more answers Helpful (1)

Will the factory serpentine belt work with these? Or will i need a different length belt?


  • The Steeda Underdrive Pulleys will re use the factory Serpentine Belt.


Helpful (0)

Would these pulleys work well with a cammed 2v mustaqng?


What is the diameter of the alt and water pump pulley? I understand it is difficult to see in photos but they look simliar to stock pulleys Can't be a big change if the stock belt is re-used unless the auto tensioner is making up for the change. I know it doesn't take a big size reduction to make small gains but I am curious of the stock diameter vs Bbk's diameter?!?!


  • The diameter of the alt and water pump pulley is 6.378 inches.


Helpful (0)

will these fit my 4.6l 2004 crown victoria. im aware that most mustang gt parts are compatible with crown victorias right?


  • While most Ford parts can be used across different model Fords, we can only confirm that the Steeda Underdrive Pulleys (Late 01-04 GT) will work on Mustangs. If you would like further assistance, please call or email us! http://www.americanmuscle.com/contact.html


Helpful (0)

Will this fit my 01 Bullitt?


  • This Steeda Underdrive Pulleys will not fit on a 2001 Bullitt. The part number for your application is 7-1-0002.


Helpful (0)

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Customer Reviews (78) Write a Review

Overall Rating 4.7

out of 5 stars

Installation Time:Afternoon

Installation Cost:$100-$250

  • Performance Gain 4.181818 4.2
  • Fit 4.969697 5.0

  • 5/5

    Installation Time: Afternoon

    December 23, 2015

    Steeda Underdrive Pulleys

    I have a highly modified 4.6L two valve drag car, that I also keep legal for the street. Because of my speed in the quarter mile I must use SFI rated parts for safety. Steeda parts, are always of the highest quality and meet the highest design standards, often working with Ford in design. Installation is straight forward, a trick to use when loosening the alternator nut is to loosen it while the serpentine belt is on, this also works with the water pump bolts. After loosening the bolts you can remove the serpentine belt. Pulling the old balancer is straight forward, put your car in gear with a standard transmission and with a puller that you can get, from a lot of auto parts stores, by borrowing their tools, remove the old balancer. Use the Steeda supplied torque specs and its an easy job that can be done in a little over an hour. Since under drives are larger than factory pulleys, always check for clearance and anything that can rub on the serpentine belt. I had to trim a protruding stud, with my Dremmel tool.


    Year: 2002 Submodel: GT St. Charles Mo.

    Helpful (1)

  • 4/5

    Installation Time: Afternoon

    January 02, 2014

    Extra HP

    It took a couple hours to get everything old off and install the new set but once we did its been a great item. It went on a 5 speed with mild bolts on.


    Year: 2002 Submodel: GT Malvern, PA

    Helpful (2)

  • 4/5

    Installation Time: Less than 1 Hour

    January 26, 2013

    Great addition

    These pullies gave my motor that brand new pep feeling from a dead stop. I haven't seen any gas mileage gain, it might be because I can't keep my foot out of it. These are a great bolt on addition and AM got them to me quick fast and in a hurry!


    Year: 2001 Submodel: GT Parris Island, SC

    Helpful (2)

  • 5/5

    April 05, 2010


    Getting the old pulleys off was a bit of a pain, especially the dampener. Putting them on was easier than expected and took about an hour-hour and half taking my time, cleaning things as I went. Felt a difference of maybe 10hp at higher rpms. Steeda's the way to go, don't go with "piggy-backs".

    Dickie Ayer

    Year: 2004 Submodel: GT

    Helpful (2)

  • 5/5

    February 19, 2010


    These pulleys are great! I noticed a quicker throttle response and pull on my 02 GT and the installation was very easy maybe15min install time!!!


    Year: 2002 Submodel: GT

    Helpful (2)

  • 4/5

    November 05, 2009

    Good Product

    Good quality part. Steeda has been making performance parts for mustang for a long time and they really kno what they r doing. These pullies run alot stronger than stock, no wobble. Didnt feel to much along the lines of power or throttle response but still a good quality product.

    Matt P.

    Helpful (2)

  • 5/5

    August 29, 2009

    03 GT Conv

    An easy install for a decent price with a modest gain on horsepower. A for sure install for the do it yourself mustang owner.

    JC Glaze

    Year: 2003 Submodel: GT

    Helpful (1)

  • 5/5

    March 05, 2009

    2002 GT

    Probably the best bang for the buck engine bolt on I\'ve bought. Noticeable increase in low end power. This with a cold air intake and catback exhaust cut half a second off my quarter mile.

    Paul H.

    Year: 2002 Submodel: GT

    Helpful (2)

  • 5/5

    February 16, 2008

    2004 Mustang GT

    A few snags in the removal of old pulleys: Even with an impact wrench, surface rust on the alternator bolt made removal difficult. The alternator bolt is standard 13/16 or 15/16. There are three tapped holes on the dampener you can use to mount a harmonic balance puller tool. I would recommend cleaning the threads with a tap first! Otherwise use a three-jaw puller. The install of the new Steeda pulleys went smoothly. They look great, especially the dampener. I noticed an improvement in low and mid band power, the engine also responds quicker.


    Year: 2004 Submodel: GT

    Helpful (2)

  • 5/5

    August 17, 2010

    highly impressed

    super easy to install, than again i am a tech, but would be super easy for anyone with proper tools, aka an impact and pully remover. i was very impressed with the mid range power gain. low end torque was increased some and also with throttle responce, but the mid range power was pretty noticable, i would definantly reccomend this to any mustang owner inless you plan to put boost to your motor because you wont be able to run as much psi with underdrives. thanks AM


    Helpful (11)

  • 5/5

    Installation Time: Less than 1 Hour

    January 27, 2012


    hands down, Steeda is the best company to go with as far as pulleys go. I definitely felt a power difference, especially in the low torque range. The car runs a lot better as well, i can actually feel that reduced engine speed giving the car more life. All in all, its a great product and I would definitely buy it all over again. Changed my mustang and also gave it double its life. Minimum power gains i got was I think 11 RWHP. If your looking for pulleys, this is the best and right one.


    Year: 2004 Submodel: GT Los Angeles, CA

    Helpful (2)

  • 5/5

    July 04, 2010

    Great product

    Pretty simple instructions, easy install, and great gains from it through mid rpm range and higher. I drive an auto and now it feels like it has so much more left at the higher rpms. And as always American Muscle is the best!

    Blake C.

    Helpful (10)

  • 5/5

    July 21, 2008

    Definitely worth it

    These pulleys were easy to put on. The only challenge is taking the old pulleys off. Heres a tip, remove the radiator overflow tank (just remove 3 nuts and swivel off to the side) and the fan ( 2 bolts, and a little wiggling) and use an impact wrench on the crank pulley as well as the alternator.


    Helpful (7)

  • 2/5

    Installation Time: Afternoon

    September 23, 2011

    Steeda Good,Pullys bad

    I bought theses pullys and AM shipped them very fast. The pullys do give good HP gains. My problem was that I had to get a new alternator. So paying 200 for the pullys and another 200 for an alternator is not worth the power gains. AM is a great place to shop for your stang I just dont want people to have to go throught what I did for these.


    Year: 2003 Submodel: GT

    Helpful (8)

  • 5/5

    September 29, 2010

    steeda underdrive Pullies

    Great product,didn't think it would make a big difference but gained 10 kms per hr on 1/4 mile.

    Clayton Hopkins

    Helpful (6)

  • 5/5

    January 30, 2010

    Quick RPM Jump

    Hi guyz this is my very first MOD for my 01 GT. I dont know much about these cars yet, but I managed to install these Pulleys easily. Right after installation RPM jumps quick and car is more responsive. So far my AC/Power Steering and all the other accessories work fine. There is a noticable gain in acceleration, BUT NOT A LOT.


    Year: 2001 Submodel: GT

    Helpful (7)

  • 5/5

    Installation Time: Less than 1 Hour

    June 11, 2012

    Smart Money on this product! Do not go with Piggy back system

    I gained approximately 2 mpg and I would say 10 hp. The car revs quicker. Excellent quality and everything fit perfectly. The new belt rides smoothly right down the center. I would not waste my time on the piggyback aluminum products. This crank pulley is built with the harmonic balancer as one unit. Ford helped Steeda design this setup. Read the instructions, have all the right tools and be able to work from under the vehicle.


    Year: 2003 Submodel: GT SoCal

    Helpful (3)

  • 5/5

    May 10, 2010

    Must Have

    I never write reviews. The alternator was hard to get pulley off of. The performance is better than expected. It is worth it in time and effort. I can't stop driving her now. My 04GT is smooth and as silk. Have someone along during replacement to assist.

    Big AL

    Year: 2004 Submodel: GT

    Helpful (4)

  • 5/5

    February 09, 2010

    Great Product

    These pullys were a great addition to my 03 GT didnt see much of a gain in power but are a very goodproduct. The best part is the crank pully isnt a piggyback system like other kits.


    Year: 2003 Submodel: GT

    Helpful (5)

  • 3/5

    May 12, 2011

    Steeda Underdrive Pulleys, 04 GT

    The product arrived promptly, looked like the high quality product I would expect from Steeda and installation was easy. I immediately noticed that when idling in drive and particularly when the ac is on the lights dim. It did not take much of a raise in RPM to brighten them back up but it was quite noticeable. I replaced the Steeda alternator pulley with the OEM pulley and this helped but there is still a slight dimming in lighting when at idle and the automatic transmission is in drive. American Muscle told me my battery was probably weak. I have not had any previous issues with my battery or charging system but am currently trying to determine my next move. I hope I do not have to purchase a higher amperage alternator because of my choice to use underdrive pulleys.

    Douglas Lance

    Year: 2004 Submodel: GT

    Helpful (6)

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