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What size exhaust is stock on a 2003 Silverado 5.3L?

This is a discussion on What size exhaust is stock on a 2003 Silverado 5.3L? within the Exhaust forums, part of the Performance category; Hi guys, Does anyone know what size exhaust comes stock on my 2003 Silverado w/ 5.3L? I think I'm about ...

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    What size exhaust is stock on a 2003 Silverado 5.3L?


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    Hi guys,

    Does anyone know what size exhaust comes stock on my 2003 Silverado w/ 5.3L?

    I think I'm about to pull the trigger on a Magnaflow universal muffler :)

    thanks!
    2003 Silverado Z-71 ecsb, 5.3L, 3.73, 265/75/16 Mastercraft Coursier AT2; Magnaflow 3" SI/SO Cat Back(p/n15778), Blackbear tune... Truck drive's better but my MPG went down slighlty w/ the same driving habits. Justin to the rescue! Stay tuned... no pun intended.

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    If you a referring to the pipes I believe it is 2 1/2 inch pipe at least that is what it was on my 01.

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    yes, thanks. I was referring to the pipe size.

    I'm look563ing to get a Magnaflow universal muffler and needed to know the size.
    2003 Silverado Z-71 ecsb, 5.3L, 3.73, 265/75/16 Mastercraft Coursier AT2; Magnaflow 3" SI/SO Cat Back(p/n15778), Blackbear tune... Truck drive's better but my MPG went down slighlty w/ the same driving habits. Justin to the rescue! Stay tuned... no pun intended.

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    I had a 3" magnaflow put on my 2000 silverado

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    I think the stock size is 2-3/4", kind of an odd size. I just ordered a SI/SO universal Magnaflow muffler myself (#14589), can't wait for it to arrive. Got it from hottexhaust.com.
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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    Quote Originally Posted by shinychevy
    I think the stock size is 2-3/4", kind of an odd size. I just ordered a SI/SO universal Magnaflow muffler myself (#14589), can't wait for it to arrive. Got it from hottexhaust.com.
    yah, I just measured it. I measured 2-3/4" outside diameter and 2-9/16" inside diameter.

    Are exhaust pipe diameters measured from the outside or the inside of the pipe?

    OK, so how do you fit a 2-3/4" stock pipe into a 3" muffler?

    Are you just cutting out the old muffler and piecing in the new muffler?

    thanks!
    2003 Silverado Z-71 ecsb, 5.3L, 3.73, 265/75/16 Mastercraft Coursier AT2; Magnaflow 3" SI/SO Cat Back(p/n15778), Blackbear tune... Truck drive's better but my MPG went down slighlty w/ the same driving habits. Justin to the rescue! Stay tuned... no pun intended.

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    Do they make 2-3/4" to 3" adapters for exhaust?

    I would need 2 if I cut out the muffler and put in a Magnaflow :)
    2003 Silverado Z-71 ecsb, 5.3L, 3.73, 265/75/16 Mastercraft Coursier AT2; Magnaflow 3" SI/SO Cat Back(p/n15778), Blackbear tune... Truck drive's better but my MPG went down slighlty w/ the same driving habits. Justin to the rescue! Stay tuned... no pun intended.

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    most use a 3" muffler and just have the gap welded up, atleast thats how i did mine. bought a 3" muffler and just welded up the gap to seal it.

    if you take it to an exhaust shop they can make an adapter to go from 2 3/4 to 3" for you.
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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    Quote Originally Posted by Underpowered
    most use a 3" muffler and just have the gap welded up, atleast thats how i did mine. bought a 3" muffler and just welded up the gap to seal it.

    if you take it to an exhaust shop they can make an adapter to go from 2 3/4 to 3" for you.

    ahhhh ok. Yah that makes sense. So they could just fill the gap with weld and skip the adapter altogether, right?
    2003 Silverado Z-71 ecsb, 5.3L, 3.73, 265/75/16 Mastercraft Coursier AT2; Magnaflow 3" SI/SO Cat Back(p/n15778), Blackbear tune... Truck drive's better but my MPG went down slighlty w/ the same driving habits. Justin to the rescue! Stay tuned... no pun intended.

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    A good shop will expand the end a little so it slips over and then they weld it up.Yes they do make an adaptor to match them up
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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    Quote Originally Posted by kaycee
    A good shop will expand the end a little so it slips over and then they weld it up.Yes they do make an adaptor to match them up

    kinda hard to expand a pipe that is already on the truck ain't it? unless you get a muffler that is already a smaller size, you can't expand it.

    however, the shop that origionaly did mine did say that if i bought a 2.5" inlet they could expand it to work with teh 2.75 but have actually split a few mufflers trying this.
    new tow Rig rattles and smokes
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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    When i got my exhaust the guy was putting 2.5" on and i asked about it being smaller then stock size. He said that GM uses an odd sized 2.75" pipe to minimize alterations to the exhuast. I dont know if that was true or not. The just welded the gap up like you guys were saying.
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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    A little pissy r we,I was just refering to how some do it
    2001 Silverado K-1500
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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    Quote Originally Posted by kaycee
    A good shop will expand the end a little so it slips over and then they weld it up.Yes they do make an adaptor to match them up
    ok sweet. I'm too cheap for an exhaust shop. I will probably order the muffler cut out the old one and get the adapters to attach the new one.

    Then when I visit my cousin, I'll have him weld it for me....

    Can you weld stainless? Or do you need to braze it?
    2003 Silverado Z-71 ecsb, 5.3L, 3.73, 265/75/16 Mastercraft Coursier AT2; Magnaflow 3" SI/SO Cat Back(p/n15778), Blackbear tune... Truck drive's better but my MPG went down slighlty w/ the same driving habits. Justin to the rescue! Stay tuned... no pun intended.

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    Does anybody know if you can weld stainless? Or do you have to braze something like that?
    2003 Silverado Z-71 ecsb, 5.3L, 3.73, 265/75/16 Mastercraft Coursier AT2; Magnaflow 3" SI/SO Cat Back(p/n15778), Blackbear tune... Truck drive's better but my MPG went down slighlty w/ the same driving habits. Justin to the rescue! Stay tuned... no pun intended.

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    stainless can be welded.
    new tow Rig rattles and smokes
    '89 K5 trail rig

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    Your local auto parts store should have some kind of adapter for your setup.
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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    Quote Originally Posted by Underpowered
    stainless can be welded.
    Quote Originally Posted by Chevy4thewin
    Your local auto parts store should have some kind of adapter for your setup.
    Thanks guys. I do want an adapter, but then I would like to have it welded. Then I guess the best thing to do is to put some high temp paint on the welds so that they do not rust, right?
    2003 Silverado Z-71 ecsb, 5.3L, 3.73, 265/75/16 Mastercraft Coursier AT2; Magnaflow 3" SI/SO Cat Back(p/n15778), Blackbear tune... Truck drive's better but my MPG went down slighlty w/ the same driving habits. Justin to the rescue! Stay tuned... no pun intended.

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    i got the same issue, i have a 02' silverado, got a flowmaster cheap for 25 bucks but its a 2 1/2 in and out. what size adapter would fit? the id is 2 1/2 on the pipes and the muffler.

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    Re: What size exhaust is stock on a 2003 Silverado 5.3L?

    My muffler shop cuts a little off the inlet on the muffler so the inlet is just large enough to fit over the pipe then welds it up.
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