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Old 11-22-2012, 03:25 PM   #1
savatreatabvr
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Correct 454 Exhaust Pipe Diameter?

My mid 70's 454 has massive 3" pipes all the way to the back, what is the factory OEM pipe diameter? If it's not 3", could the pipes being to large hurt my performance?
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Old 11-22-2012, 03:34 PM   #2
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Re: Correct 454 Exhaust Pipe Diameter?

The stock diameter on my 79 454 were 2 1/2".

I've run dual 3" on mine for years with the 454 (now a 502) with long tube headers and quality mufflers. Works great.
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Old 11-22-2012, 03:42 PM   #3
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Re: Correct 454 Exhaust Pipe Diameter?

Your fine. Your exhaust manifolds are killing more power at this point
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Old 11-22-2012, 03:52 PM   #4
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Re: Correct 454 Exhaust Pipe Diameter?

You still have manifolds?
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Old 11-22-2012, 05:25 PM   #5
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Re: Correct 454 Exhaust Pipe Diameter?

My r30 TBI 454 truck has factory 3 inch single exhaust.
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Old 11-22-2012, 11:23 PM   #6
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Re: Correct 454 Exhaust Pipe Diameter?

LOL, yep I've still got stock exhaust manifolds! I do plan on getting headers one of these days but right now I'm just trying to keep it running as good as I can for as cheap as I can! Anybody got a cheap set of big block headers laying around?

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Originally Posted by Firebirdjones View Post
You still have manifolds?
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Old 11-24-2012, 08:45 AM   #7
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Re: Correct 454 Exhaust Pipe Diameter?

don't know if you have these but some grinding may help keep it cheap and flow better
i always find the sound gets louder/better
smooth out the flow has gotta help
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Old 11-24-2012, 10:27 AM   #8
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Re: Correct 454 Exhaust Pipe Diameter?

If you are really bent (or rule restricted) to keep the stock manifolds, after initially porting on them like Motornut mentioned above, I send them out to be extrude honed. Keeps that stock appearance and picks up several HP
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