2.5" or 3"

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kg340

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I have a 73 Duster w/ a 71 340 Forged crank 10 to 1 comp. Mp. 509 cam, single plane M1 , 2.02 heads 8 3/4 sure grip w/ 3:91 , hooker comp. headers.which exhaust should I go with? 2.5" or 3" ?
 
kg340 said:
I have a 73 Duster w/ a 71 340 Forged crank 10 to 1 comp. Mp. 509 cam, single plane M1 , 2.02 heads 8 3/4 sure grip w/ 3:91 , hooker comp. headers.which exhaust should I go with? 2.5" or 3" ?
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Whats the size of the outlet of headers, 2 1/2?
 
kg340 said:
yes
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Then that's the "minimum" size. I'd recommend 3" if space allows, and go the extra expense and get the pipe mandrel bent. It looks better, fits better and restrictions are minimized. Also consider a crossover or H pipe since you're redoing the header back exhaust system anyway.:evil2:
 
I'm guessing street Duster. It'll use a 2-1/2 inch exhaust. 3 is a waste at this point.
 
Had a guy say good things about pypes for his Magnum. Though they were not designed for it. He just added extra pipe to make up the length. He got the kit for early B bodys while his is a later B body.
Got a link?
 
FWIW, There was an article in one of the mopar rags a few years back where they put a small block Challenger on a chassis dyno to test exhaust systems. I do not recall the actual numbers for each test but;

They base lined the car with headers and a compression bent 2.25" dual with stock type mufflers and no crossover. The first upgrade was to go to Dynomax Super Turbo mufflers (I pretty sure that's the muffler they used) and got a significant imprevement. The next test was to go to a mandrel bent 2.5" system with the same muffler and a cross over. There was a very significant improvement, more than the muffler change on the 2.25" system and the noise level went up significantly but was still acceptble (to them) for a street car. The next test was a mandrel bent 3" system, cross over and the same muffler. They saw an improvement in power but it was very small, but the sound level went up dramatically over the 2.5" system to the point they didn't feel it was worth the expense or to put up with the noise.

When I swapped the 360 into the Barracuda I was using the 2.25" dual system with an H-pipe crossover and 18" glass-paks that I had for my slant 6. After about a month I installed a new system that was 2.5" pipes, x-pipe cross over and Flowmaster 50 series delta flow mufflers. The butt dyno did not register any power improvement but the noise level went down considerably from the system with glass-paks and it has a better tone.

IMHO, unless you are looking to squeeze out every last pony and are willing to put up with a LOUD system I would stay with 2.5".
 
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