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Exhaust Pipe Size coming out of Long Tube Headers

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by BigNate7470, Jul 11, 2013.

  1. BigNate7470

    BigNate7470 New Member

    Hey Everyone- I'm putting some long tube headers on my 2005 1500 Sierra w/ the 5.3. I've been doing some research and found that most people suggest going with a 2.5" pipe for true duel exhaust. With that said the stock diameter coming out of the stock manifolds is 2.75". Would I lose much by running 3" pipes from the header to a magnaflow 2 in (3") 2 out (2.5") muffler? Or should I reduce the pipe size to 2.5" right out of the headers and just go with the muffler being all 2.5" ins and outs? Just figured I'd get a little more input before purchasing the muffler. Thanks
  2. buckmeister2

    buckmeister2 Member 1 Year 100 Posts

    header to muffs question

    sorry is this is a double post...Keeping in mind that your truck is essentially stock, there won't be any problems reducing to 2.5" coming off the headers. You are running two pipes into the muff, and two out, so I can't imagine there being any backpressure issues. Running 3" pipes into the 2.5" muff will be the same as running 2.5 all the way. Since you are using a Magnaflow muff, I am sure their tech line would be glad to take your call with any questions. Jim
  3. TimTom64b

    TimTom64b Member 2 Years 500 Posts ROTM Winner Gold Member

    That is plenty... most performance exhausts such as corsa using a single inlet dual exit exhaust run a 3" pipe up front with 2 1/4-1/2" tailpipes. Is there a reason you do not want to run a x-over pipe? Doing so will make it easier to tune as it provides for a more equal/consistent back pressure for all cylinders. Just something to consider.

    Sorry I didn't catch the dual in dual out muffler... this accomplishes the same thing as a x-over pipe. Guess this is the downside of using my phone to access the forum.

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