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Discussion Starter #1
in regards to pipe size, i know there's lotsa variables, but if i could get a general idea, i'd thank ya...

would i gain HP by using 3" instead of 2-1/2 pipe ???



i'm planning on using Thorley Tri-Y's with a couple different possibilities on pipes/mufflers. either chambered exhaust with an X, or the Dr. Gas BoomTubes with an X, or, i already have a dual 2-1/2 in/3" out flowmaster... in which case i'm kinda stuck with the pipe size of 2-1/2.

i plan on either duals out the sides in front of rear wheels, or the single out on the left... in front of wheel


thanks, i know there's LOTSA variables... anyone wanna throw out some thoughts ??? ;)
 

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just my thoughts on this but I'm not totally convinced that in most cases a 3" exhaust system is called for....I would run the 2.5" if I were you......I think someone on here has a program for figuring out the perfect exhaust system...possibly something like that would help you out;)
 

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i say go with the 2.5", 3" will be much harder to route and (i forget your engine combo) most likely not needed...heres some pics of exhaust i bent up the other day for my 63...i did the first one, tried to do something different and didn't like it so i made up the x pipe deal, but i will be buying a aftermarket x section because it was very hard and i don't think it will flow as good going throught the one side as the other....2.5" BTW i used the same after muffler section for both









 

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Most of the power difference in an exhaust system is in the first 6' behind the engine. Once you get to the tertiary pipe you're pretty much down to deciding how loud you want it and where it's going to exit.
 

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I think I remember seeing a segment on "Two guys garage" about exhaust technologies. I believe they talked about the collectors being an important role. Has anyone heard this info?
 

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stinger670 said:
I think I remember seeing a segment on "Two guys garage" about exhaust technologies. I believe they talked about the collectors being an important role. Has anyone heard this info?
If you do a little research you'll come up with good info. Rodney Davis has an excellent calculator that'll come up with a reasonable design for your headers.

http://www.headerdesign.com/

Jack Burns of Burns Stainless has written extensively about this subject:

One of the largest errors street enthusiasts make is in running too large of a primary pipe, and too large of a collector. For example, NHRA and IHRA Stock teams using Burns' headers in H/SA in traditional small-block powered musclecars are running 1.5-inch diameter primary pipes- much smaller than many street machines are trying to use.

http://www.popularhotrodding.com/tech/0310phr_burns/

We used 1-5/8" x 2-1/4" merge collectors on the 331" Durango Deuce motor.
 
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