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Exhaust Pipe Size coming out of Long Tube Headers

1333 Views 2 Replies 3 Participants Last post by  TimTom64b
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
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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
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