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  • Madness MINI Cooper lightweight 15% and 19% supercharger pulley
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Madness MINI Cooper S Supercharger Pulley

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Product Description

For a minimal amount of money, the MINI Cooper S Supercharger Pulley can make even the Monday commute seem like a run around Laguna Seca. The stock pulley is one of the first things MINI Cooper S owners replace to increase the performance of their car. Changing to a 15% smaller supercharger pulley on an otherwise stock motor has been shown, through independent testing, to provide increases of 15-20 horsepower with similar increases in torque.


The smaller supercharger pulley causes the unit to spin faster and create more boost. More boost=bigger grin! Stock Mini Cooper S engines will see a 4-4.5 pound increase in boost. Add to that a modified intake or exhaust and your Mini Cooper S will have even bigger power gains. MINI Cooper S tuners, including the venerable John Cooper Works, have extensively tested the 15% reduction supercharger pulley and found it to be ideal for street and track use.


Included is an installation CD and tool that with a moderate amount of mechanical ability makes installing the supercharger pulley the ideal weekend project. We've been told that it makes a great gift for the Mini Cooper S Enthusiast too.


For the even more adventurous, changing to a 19% reduction pulley will have the boost kicking in 750rpm sooner than the 15% pulley.


The 19% Mini Cooper S Supercharger Pulley is ideal for street driving conditions ONLY! It is not recommended for the long high revving situations typically seen on the racetrack!  Sustained 6000-7600rpm generates more heat reducing the 19% pulley's effectiveness.

There simply is no greater bang for the buck out there.


This pulley is made from aircraft quality 6061T6 heat treated aluminum and uses a taper fit design for easy installation. Securing the pulley are 6 grade 10 stainless steel bolts.  This ensures equal distribution of clamping force, zero corrosion and strength needed for this application. We've also anodized the pulley black to maintain a stock appearance thus avoiding any blatant indication of the upgrade. Stealthy, just the way we like it!

Rotational weight is a critical factor that impacts supercharger performance. Other pullies on the market that are made of stainless steel weigh more than the stock pulley! This directly affects how fast the supercharger reaches full boost.  Madness pullies weigh less than half the weight while maintaining excellent reliability.

Stock MINI Pulley       = 11.0oz/311g

Stainless steel 15% pulley = 16.0oz/501g
Stainless steel 19% pulley = 13.2oz/374g

Madness lightweight 15% pulley =   5.5oz/155g
Madness lightweight 19% pulley =   5.0oz/125g


Using our simple pulley removal tool allows you to remove the stock pulley with ease. Most removals take just 5-10 minutes. Our removal tool also does not destroy the stock pulley allowing you to reinstall it if necessary. Failure to remove factory pulley properly can result in shaft misalignment theefore rendering the supercharger useless to the tune of $2100.   Return tool after use for a $60 store credit good for one year.
Our self alignment pulley ensures 100% accuracy during pulley installation ensuring no thrown belts from improper installation.
Included with every kit is a CD containing installation instructions with lots of pictures to assist you or whoever you might have doing the work.

Also recommended are a set of cooler running spark plugs.  This simple upgrade gains you 1-3hp and more importantly helps prevent and pre-detonation that might occur from higher boost temperatures.  Cooler running plugs help transfer the added heat into the cylinder head helping to reduce in cylinder temperatures by a few degrees. This helps prevent and pre-detonation from occurring. Inexpensive insurance is the way we look at it.

Madness MINI Cooper lightweight supercharger pulley
All I can say is "Wow are you kidding me?"
Eric Kurkey (Belleville, IL) 9/3/2013 7:12 PM
Just got my Mini back from the shop. Had the 19% pulley installed. Along with the Milltek header, cat and cat-back exhaust, Madness CAI, cowl mod and MSD coil and wires. Also had new head and supercharger installed as my Mini has 192,000 miles and needed a refresh. I haven't had the chance to really test the new power yet as I need to run thru a break in period. But even at 2/3 throttle and 4500RPM max I can tell this is going to be epic. Thanks for all the advice, George. Much appreciated.
Very noticeable
Brock Needham (Dickinson, ND) 8/17/2011 12:42 AM
I noticed the biggest change in 3rd gear, the engine seams to still have a lot of pull when it used to drop off. Can also notice that the power kicks in at lower RPM than before.
Love the 15% reduction pulley
Dale Jorgenson (Hillsboro, OR) 7/20/2011 2:32 PM
WOW! George was right. Big difference with this pulley. I was having some work done on my mini and since they had it pulled, I had George and his team install the pulley and now I have to watch it because I want to race to every stop light. Way worth it. People will be wondering what just passed them. Thanks Mini-Madness.
Russel Kennel (KEIZER, OR) 2/10/2011 9:17 PM
Mini Madness installed a 15% puller, CAI, and Evotech custom remap tune. The tune is a must if you want the car to run right. Here are the benefits of this. 1. Instant, solid smooth linear torque from 1800 RPM and up to redline. 2. The engine wants to rev and pull hard at 6,000 plus instead of weakening. So, you really can have your cake and eat it too - power at both ends of the spectrum. 3. Smooth shifting - the engine responds instantly to the throttle, making it easier to match revs with the car. 4. Feeling: Acceleration is like a falling rock in any gear. 5. The price was reasonable, and having George perform the modification is worth paying to have it done right the first time!
(Unknown) 11/14/2008 4:29 PM
the 15%... all i can say is, its crazy the difference it makes! you will be glad you got it!
Mini Roids!
(Unknown) 7/25/2008 7:54 PM
I purchased the 15% reduction pulley along with the recommended cooler running spark plugs. This upgrade made a HUGE!!! improvement. I couldn't believe it was my mini! Absolutely amazing! This is my second purchase from George and the gang, and I rest easy knowing their parts are in my vehicle. FYI: You made also need to replace belt tensioner and belt if they are worn. Be prepared for this when having installed. Thanks again for all your hard work George. -Brendan Duluth, GA
Best Bang for your Buck!
Anonymous (Unknown) 5/9/2008 3:23 PM
The Madness 15% reduction supercharger pulley, paired with the MM cold-air intake will be, without any doubt, the best money you'll ever spend on you Mini Cooper "S". Over 25 horsepower gains for just a couple of hundred dollars? A real no-brainer being as you usually have to spend thousands to get those kinds of increases. Thanks!!! OP
Part of a compete package, Step 1
ex997guy (Unknown) 7/27/2007 5:45 PM
The first step on the way to Madness stage two was a 15% pulley. I'm mechanically competent and after looking things over and noting the need for a pulley removal tool, I did the only sane thing and had George install it. The immediate gain in horse power was pretty amazing. There were no drivability issues and the fun factor of a car that was already great increased dramatically Best bang-for-the-buck modification going. The car ran rich after installation, as was expected.
A Must Have!
(Unknown) 6/22/2007 4:20 AM
The Madness pulley definitely brings out the part of the Mini S that you wish was their in stock form. The installation was fairly simple with minimal mechanical know-how (3-4 hours) and the step-by-step picture instructions made that much easier. Passing people became that much more fun with the supercharger whine, it went from "Hey I got passed by a Mini", to " What the heck was that?"
(Unknown) 5/25/2007 12:12 PM
"the installation instructions provided were top notch allowing my mechanic to complete their first time installation in under 3 hours. My Cooper S now feels the way it should have from the factory" Sharif Nadir, Seattle
(Unknown) 5/25/2007 12:07 PM
”I just wanted to take the time to praise you for your pulley and puller kit. I purchased one last week on the web and within four days had it installed. The product is of good quality, the puller a huge help, and the instructions easy enough for an illiterate child to follow. What more can I say but that my MINI is now a car that I love to drive. Before my MCS just did not feel sorted. There were times when I got so damn exasperated at the thing's lack of lower end and hustle. Now, with only your pulley, my MCS really hustles! Finally I have the car I wanted and I might not even be sad to have it replace my SC Miata! This is really saying a lot!" Ian F. Griswold
(Unknown) 5/25/2007 12:05 PM
"holy crap! I just can't believe how good this feels!" John Moore, Winston Salem NC
15% Pulley Rocks!
wpotere (Unknown) 4/17/2007 12:26 AM
This is by far the most hp for the dollar. The MINI-Madness pulley is a two piece pulley and installs in about 3 - 5 hours (provided you know what you are doing). The install is not for the technically challenged as it does require some work, but the effort of getting this done is well worth it in smile factor! :) The MINI is more aggressive at the lower RPM range and definitely has more punch. A must for all MINI owners. :)

Product Reviews

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  1. !!ALL KINDS OF AWESOME!! 5 Star Review

    Posted by on 8th Jun 2018

    My shop put in with a few other upgrades and MAN!! I now have a land rocket. NO MORE SLUGGISH FIRST GEAR!
    It's my wife's daily driver and she tells me stories regularly of people who think they are going to block from entering the highway and finding themselves quickly in the losing mirror.... and we laugh...

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