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  1. #1

    Exclamation Need help with muffler sizing

    I have a 1988 gmc sierra 3500. i need a new muffler and dont know what size to buy. The pipe diameter is 3 inch. does this meen i buy a 3 inch inlet and outlet muffler.

  2. #2


    Yeah my my muffler is a flowmaster 40 series and is dual in dual out which is 4 holes two on each side where the exhaust weld on. Also is the pipe the same size all the way down? Anyway bro you will need a 3 inch diameter muffler and single in single out or single in dual out basically whatever setup you go with if you have stock exhaust just single in single out but can make it look like true duals with a single in dual out. Anymore help ill be glad to answer?

    2008 Chevy Silverado Ext. Cab Lt Z71 5.3 V8
    7.5 Inch Rough Country Suspension Lift
    RBP Replica Grille Black w Chrome Rivets
    Recon Smoked Cab Roof Lights
    N-Fab Powdercoated Gloss black Cab Length Nerf Steps
    5% Tint over 20% all the way around / 5% Eyebrow Strip
    AVS Smoked Window Visors
    Z71 Stickers Black & Metallic Silver
    Tow Mirrors / Smoked Turn Signals
    XM Satellite Radio Fin / Color Matched
    Interior Plastic Pieces / Color Matched
    Power Acoustic Tweeters
    Painted Bowties / Color Matched
    Painted Door Handles / Color Matched
    Smittybilt Bull Bar / Color Matched
    Custom Rolled Edge Exhaust Tips / Color Matched
    Custom 2.5 Inch Cat Back True Dual Exhaust
    Flowmaster Super 40 Series Dual in / Dual out
    Magnaflow Tru-X Pipe
    K&N Air Filter
    18x9 Rockstars Machined Black
    Center Caps / Color Matched
    33.13.50 Nitto Terra Grapplers
    New Front Wheel Well Liners
    Eagle Eye Black L.E.D. Tailights
    Eagle Eye Black L.E.D. Third Brake Light / Smoked
    Eagle Eye Black L.E.D. Halo Projector Headlights
    Notto HID Kit 10,000k Low beams
    Recon L.E.D. Light Bar
    Buschwacker OE Style Tailgate Cap
    AMI Gloss Black Antenna
    Debadged Chrome Lettering
    Door Molding Removed

  3. #3


    Im looking at a cherry bomb glasspack. My pipe diametre is 3 inch outside to outside but is 2 3/4 on the inside of the pipe and the section of pipe where the muffler is is 3 inch pipe then it goes into 2 1/2 inch tail pipes. Will a 3 inch muffler still work. Also any expeiriance with installing a muffler.
    Last edited by Outlaw19; 02-10-2012 at 04:19 PM.

  4. #4


    Adapters are a great way to make square pegs fit in round holes
    2010 Chevy Silverado Z71 ext cab.4x4
    72 Monte Carlo 350-415 hp- sold (June 2011) to pay medical bills
    79 Impala 350 4bbl 375 hp- sold (June 2011)to pay medical bills

    "If He asks you to go a mile go two"

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