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2003 GMC Sierra Performance Mufflers

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Latest Customer Reviews

Flowmaster 70 Series Big Block II Mufflers Reviews

A great mellow, growl and improved performance over stock

Reviewed By Thomas B (Brighton, MI) Reviewed for a 2003 GMC Sierra —7/11/2010 12:20 PM

Well, a couple of years ago I purchased two Flowmasters Super 44 mufflers to go behind my two catalytic converters. These went on my 2003 GMC Sierra 1500 HD (Crew Cab with 6' short bed) 6.0L V8. I was excited since I would have true duals and the loudest mufflers that Flowmaster made. They sounded like a hot rod on the outside and the inside resonance and noise was terrible, especially around 25 mph and 75 mph (horrible roaring/annoying sound). After a year, I had to get rid of them and put my stock back on. I needed something aftermarket, but wanted a deep mellow tone with good low end power for my truck. Behold, the 70 series big block II. A great sounding muffler that lets you know you have a powerful muffler, but not annoying in the least bit. The inside resonance is not even there - a low mellow sound when you hit the gas pedal and then it disappears when you cruise at 20, 30, 40, 50, 60, you get the picture. A great muffler for the person who uses their truck, suv, etc for everyday use, work, towing, family activities, etc. If you're looking for something crazy loud, inside cab and out, go with something else (a friend told me that even the 50 series big block is a little too loud for this truck, if you looking for low and mellow). But if you're looking for a mild, good strong, a little throaty sound with increased torque and towing power, this 70 series big block II muffler is for you. Check out the reviews and videos online. Hope this review helps you out.

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Flowmaster Super 50 Series SUV Mufflers Reviews

Everything I'd hoped for

Reviewed By D. Thomas B (Topeka, KS) Reviewed for a 2003 GMC Sierra —4/10/2007 7:20 PM

Had Midas install as I can't weld. Sound is cool, but not obnosious. Performance seems improved, but I added this with a performance chip and so can't judge the muffler on its own. I am most satisfied.

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Flowmaster Super 10 Series Mufflers Reviews

Not too shabby

Reviewed By Zackary A (BINGHAMTON, NY) Reviewed for a 2015 GMC Sierra —4/14/2017 8:19 PM

Too quiet with just the muffler . Had to cut out the resonator. Sounds pretty throaty now probably perfect for a lot of people .

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