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  1. #1

    Default 5.3 Exhaust Advice

    Today I went to my local muffler shop, I told him I wanted loud so he recommended two setups. The first would be a SI/DO Flowmaster10. Then he showed me a gutted out glasspack that would be Y-piped out. Was wondering which would sound better and louder on a 2013 Silverado 5.3.

  2. #2
    Master Mechanic BurbanMan's Avatar
    Join Date
    Jul 2013
    Dolores, CO


    Quote Originally Posted by ZRouse07 View Post
    Today I went to my local muffler shop, I told him I wanted loud so he recommended two setups. The first would be a SI/DO Flowmaster 10. Then he showed me a gutted out glasspack that would be Y-piped out. Was wondering which would sound better and louder on a 2013 Silverado 5.3.
    the flowmaster 10 would be better IMO.

  3. #3


    Id go with the flowmaster, the 5.3 with afm doesnt like a large open exhaust, it loses to much low end for low speed driving.
    I used a Flowmaster 40 on my 2011 5.3 with dual 3" out, kept it a week before I pulled it out and put in a magnaflow with dual 2.5 out.
    The pipe size made the largest difference, If I redo it again I might use dual 2" out, Ive seen/heard a system like this and its a little more responsive like this.
    Remember AFM is a very picky system when you make changes to the engine.

  4. #4

    Default chart/formula

    Just kill the AFM. tb is correct, I know guys want a huge set of pipes these days, but the 2 to 2.5 inch sound way better, and no 4 inch echo nipple on the end of the tail pipe. Happy hunting and good luck in your choice.

    Your intake system needs to flow 1.5 CFM per engine horsepower, and your exhaust system needs to flow 2.2 CFM per engine horsepower.
    A good section of straight pipe will flow about 115 CFM per square inch of area. Here’s a quick table that shows how many CFM each common pipe size will flow, as well as the estimated max horsepower for each pipe size:
    The table below is probably over-estimating pipe size, but you can see that a 400 hp vehicle with a dual exhaust system only needs 2 1/4 – 2 1/2 inch pipes. Anything larger is overkill.

    Pipe Diameter (inches) Pipe Area (in2) Total CFM (est.) Max HP Per Pipe Max HP For A Dual Pipe System
    1 1/2 1.48 171 78 155
    1 5/8 1.77 203 92 185
    1 3/4 2.07 239 108 217
    2 2.76 318 144 289
    2 1/4 3.55 408 185 371
    2 1/2 4.43 509 232 463
    2 3/4 5.41 622 283 566
    3 6.49 747 339 679
    3 1/4 7.67 882 401 802
    3 1/2 8.95 1029 468 935
    Last edited by summitwhite11; 01-07-2014 at 06:29 PM. Reason: adding chart and formula
    Life is short compared to history

    Rick (summitwhite11)

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  6. #5


    I had installed the Flow/Master Super 10 and dumped over the rear axle and it sounds GREAT! Loud outside but not to much in the Cab....
    2010 GMC SIERRA CREW CAB (Silver) 4x4, ReadyLift 2.5" Level Kit, 305/60/18 Dick Cepek Mud Country, Go Rhino Nerf Bars, Husky Liners front and rear, Bushwacker Bed Rail Caps, SCT Programmer.

  7. #6


    Magnaflow stainless one in two out, nice growl at take off and no in cab drone. Had it for about six months and still love it. Get yourself a ranger or intune a kill the AFM. Night and day!
    I am a American solder, I am a member of the finest fight force on earth, I am the bump in the night. I will defend the United states of American Against all enemies both foreign and domestic. Repent now all those who would do my nation and it's people harm; For when we come it will be too late.

    2011 GMC Sierra SLE, Z71 with 5.3 l and max tow/haul package

  8. #7


    Nice chart Summitwhite. I havnt seen this one before but it replicates standards Ive used for years when building exhaust systems.

  9. #8


    I went with a Flowmaster Super 40 single in duel out because I like the look of two pipes out of the back. Great sound at start up and acceleration. You can hear it in the cab a bit, but that doesn't bother me I wanted that. Mine uses the stock headers and cats as of right now (still wanted to hang on to me warranties) so it is essentially a cat/back exhaust. I used this set up on both a 2013 and 2014 very happy with it.

  10. #9
    Sr. Mechanic Cowpie's Avatar
    Join Date
    Jun 2013
    Central Iowa


    I guess it all depends on what a person wants for decibels. I have had dual setups in the past that sounded like I was at a Sturgis motorcycle rally. I have since gotten wiser. I really like the results out of my relatively inexpensive Dynomax cat back single out on my 2013 5.3. Nice, deep, throaty sound that is not overpowering. They know you are there, but they don't get ticked off at the noise.

    Oh.... ditch the AFM on the engine to make your exhaust mod worthwhile. I shut off the AFM on my engine the day after it came home new from the dealership. Never regretted it. From many users I have read that shut off the AFM, they have not experienced any degradation to their fuel mileage numbers. Some claim, though I won't do the same, that their mpg actually went up a little. Each case is different. Either way, your engine will be more pleasing, and your exhaust more enjoyable if the AFM is shut down.
    2013 Silverado 1500 LT Z-71 Crew. 5.3L Auto. Range AFM Delete, PCV Catch Can, RC Leveling kit, Dynomax Ultra Flo cat back, Airaid M.I.T.

    2013 Freightliner Columbia. pre-EGR Detroit 12.7L 500 hp 1850 lb torque, 18 speed.

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