(approx) 2 Hours
Light to Moderate mechanical skill required.
Justin: Hey, I'm Justin with AmericanMuscle.com and this is the Stage 2 Power Pack Bolt-On Build-Up for all 2007-2009 GT500s. This Power Pack is for the GT500 owners who have already taken care of some of the basic bolt-ons; your cold air intakes, your tunes, and are looking for more power out of your supercharged 5.4 liter. Now if you guys are looking for more power out of your Mustang, whether it's a GT500, a GT, or a V6, be sure to check out some of our other Bolt-On Build-Ups by subscribing to our YouTube channel if you haven't done so already.This entire pack is centered around a very popular supercharger mod that's going to increase our boost and therefore increase the horsepower on our GT500. However, just like anything else in the forced induction world, you can't just add more boost without addressing other key areas of your ride to ensure you're getting the most out of each mod, but more importantly to ensure the safety of your motor. So first, let's get to everybody's favorite topic, more boost. The first mod in our Power Pack consists of the Metco Motorsports 2.6 Inch Upper Pulley. Now a smaller pulley like the Metco here is always a very popular choice with supercharged applications because what it's going to allow you to do is spin that stock blower much faster, resulting in more boost. In fact, we should be looking at three to four pounds of additional boost compared to the stock three inch pulley. The Metco itself is a very nice piece and is actually very popular with other GT500 owners here on the site. In fact, if you want, you can just click on the link below to read up on some of the reviews. Now the design is a two piece design, so you have a hub that presses onto the blower shaft first, and then the actual pulley bolts to the hub using the included hardware. This is just basically going to make any future pulley swaps a complete piece of cake. I really can't wait to see what a few extra pounds of boost are going to do to our power number, and best of all, that factory Eaton blower should really be screaming.With the pulley out of the way, let's talk about some of those other supplementary mods that I told you guys about at the beginning of the Pack. Now again, you can't just bolt up a pulley and go without addressing some other areas. Case in point, that smaller pulley has now created some excess slack in our belt which basically our factory idler will not be able to keep up with. What this is going to result in is dreaded boost and power robbing belt slippage. Enter the Metco Double-Bearing Auxiliary Idler Pulley Kit which we also installed on our '08 here. Now this is going to take up the extra slack created by the smaller 2.6 inch pulley and just create plenty of belt wrap to prevent any belt slippage, and more importantly it's going to ensure that those boost levels stay rock solid all the way through the upper RPM range. On top of that, the double bearing construction will ensure a little bit more durability over time, it might actually be a little quieter, and for a few bucks more it's really a no brainer. Finally there's one more part to go over before we bring in Mike J from Bama to tweak the tune a little bit for us, and of course turn the rollers one more time. With that pulley in place, we're really going to be spinning our blower a lot faster than we were before which of course will lead to more boost meaning we had to address our spark plugs. So we installed the NGK TR6 Plugs which really are the go-to spark plug for any Shelby owner who is upping their boost. They're a one heat range colder plug compared to our stock plugs which will help avoid any possible detonation. An important note, just make sure they're gapped correctly before install to avoid any spark blowout. Definitely recommend doing these plugs or something similar whenever you really start cranking up the boost like we are here with the '08.Alright, well with all the new parts in place, we have Mike J from the Bama Performance Team in here working on the new tune for us for all increased boost that we're going to be seeing thanks to that smaller pulley. Now Mike, obviously the car's going to be seeing a lot more boost than we were before. How does that affect things on your end?Mike J: Well basically with the higher boost levels, we're going to be seeing right around 12 to 13 pounds. I've already gone ahead and made adjustments to the ignition timing tables to make sure that we're not going to see any detonation at all. I'm then basically just looking at air-fuel ratio to make sure we're in that sweet spot.Justin: Awesome man, I know those colder plugs should definitely help with that detonation too. Mike J: Absolutely.Justin: Very cool, man. Well if you're all finished up, I want you to hop on out of there because I think it's my turn. I get to hop in, do another pull, and see what the numbers are.[engine noise]At the end of the Stage 1 Power Pack featuring our 2008 GT500, the car was making 508 horsepower and 479 pound feet of torque at the rear wheels. With all the Stage 2 modifications in the Power Pack installed, we were now putting down 548 horsepower and 545 pound feet of torque making for a gain of 40 horsepower over our Stage 1 numbers, and gains of 66 horsepower and 71 pound feet of torque throughout the curve. The Stage 2 Power Pack with pulley and supporting mods is always a favorite of GT500 owners, and I think it's pretty easy to see why. Honestly, there's nothing that compares to swapping those upper pulleys and really cranking up the boost.Hey, that's going to do it for the Stage 2 Power Pack Bolt-On Build-Up for all '07-'09 GT500's. Be sure to check out the other Power Packs for the GT500s and don't forget to subscribe to our YouTube channel if you haven't already. Thanks again for watching, and for everything Mustang, keep it right here at AmericanMuscle.com.
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Features, Description, Reviews, Q&A, Specs & Installation
Fitment: 2007 2008 2009 2010 2011 2012 2013 2014
CA Residents: WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov
May 02, 2019
Definitely helps with the belt slippage, and looks great under the hood. Only issue is a lil noisy while cold until unit warms up. Hoping bearing squeal will go away as unit breaks in.Helpful (0)
April 06, 2019
Good product and easy install. Looks great and is very quiet. Still get some belt slip at high rpm's after coming off the dyno.Helpful (0)
February 04, 2019
Auxiliary Idler on 2010 Shelby GT500
Bought the Aux idler because I could feel the power kinda surging under high boost. I have the 2.5” pulley and 90mm idler installed. The Aux idler was the last thing to try before I went for a compression test. The Aux idler made a HUGE difference. The belt, which was a brand new Ford replacement belt, must have been slipping big time!! All my friends noticed a difference. I’m guessing, if I had to put a HP figure to it, 30-40 HP gain from the belt not slipping. I was putting down 520whp/536ft-lb torque. I haven’t had a chance to get it re-dyno’d at Pro Dyno since the Aux pulley install but I’m looking forward to seeing Dan for a dyno run and maybe a re-tune.Helpful (3)
December 10, 2018
Great product, a must when upgrading to a smaller pulleyHelpful (3)
November 29, 2018
Great pulley, great service from AM
Easy install. Works like a charm. The pulley is high quality, make sure to have some thread locker on hand prior to avoid a trip to the store.Helpful (3)
October 21, 2018
Good accessory. Works as intended. Install was simple just ensure you use lock-tight so it cant vibrate loose.Helpful (3)
October 11, 2018
Metco auxiliary pulley
Great product easy installation....maybe 30 minutes to an hour depending on skill level ...AM is #1 in my bookHelpful (3)
October 09, 2018
Dang! what a difference in HP!
Added a smaller pulley and the Idler pulley to my 2007 Shelby GT500. Never ran so good! Love it!!!Helpful (3)
August 23, 2018
Works as advertised
This product works great if you have a GT500, but it doesn't match up on the hardware side when it comes to a 2013 ROUSH Charged GT.Helpful (5)
July 09, 2018
2013 Shelby GT500
Easy Easy Easy to install, unless you drop a bolt. It took me at least two hours to find that dang thing. Looks good on the front of the motor, makes everything look like it needs a polish.Helpful (5)
comparison with single bearing Is having the double bearing better than the single bearing version?
Yes 2 bearings make it more stable and giving you a longer lasting pulley.
will this work with the Steeda 2.65 pulley?
Yes this will work with your 2.65 inch pulley on the stock blower
Can you use this with stock setup on a 13gt500 or is this only for use with aftermarket supercharger pulleys?
This is only for use with a smaller than stock pulley.
Does this product fit a Kenne Bell 2.8 water cooled super charger?
The Metco Motorsports Auxiliary Idler Pulley Kit is designed for the factory supercharger on the GT500
Can you use this with a Whipple supercharger?
This Metco Supercharger Double-Bearing Idler Pulley Kit is specifically designed for use on the 2007 to 2014 Shelby GT500 Mustangs equipped with the Supercharged V8 engine, that have upgrade to a 2.4", 2.6" or 2.8" Metco Motorsports Supercharger pulley. It will not fit with a 4.0L Whipple supercharger.
Yes it will work with your 2.4" pulley setup.
Unfortunately, this part does not work on ROUSH cars. Your motor is a 4.6L, this bracket is made for the 5.4L GT500 which use a totally different platform. You idlers should not be making noise regardless of cams or idle speed. I suggest you remove your supercharger belt and spin each pulley by hand. You will find one that is rough, loose or gritty feeling. Replace it. I have had issues with aftermarket billet pulleys where the bears keep failing prematurely. Stick to the boring factory pulleys, they last a lot longer. To get more boost, you need to buy a smaller supercharger pulley and a bigger idler pulley; trying looking at VMP Tuning for supercharger pulleys.
No, this does not affect your supercharger pulley. You are just adding another pulley to increase belt wrap.
(approx) 2 Hours
Light to Moderate mechanical skill required.
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