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57rookie · 10-29-2017, 01:27 PM

So I figured it out. I re measured using piece of tape and it is actually 7.75" in circumference. Then you calculate and it came out to 2.468" diameter so my factory exhaust at the inlet of the single muffler is 2.5". I knew it looked larger than 2". The tail pipe is 2".

10-29-2017, 01:27 PM	#5
57rookie Registered User Join Date: Jul 2011 Location: Calgary, Alberta Posts: 153	Re: Exhaust diameter for a 71 stock GMC So I figured it out. I re measured using piece of tape and it is actually 7.75" in circumference. Then you calculate and it came out to 2.468" diameter so my factory exhaust at the inlet of the single muffler is 2.5". I knew it looked larger than 2". The tail pipe is 2".