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Dual Exhausts

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Old Dec 28, 2005 | 01:48 PM
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Default Dual Exhausts

I recently put a new exhaust system on my 81. I left the H pipe cat assembly out and just did true duals straight back to Flowmaster 40 series mufflers.

Can anyone offer any comments good or bad? I wanted to get a few more ponies out of that choked 350, but I don't want to mess anything up either ...
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Old Dec 28, 2005 | 02:18 PM
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you need a crossover pipe, aka H or X and you will be good! get a offroad one and you will be good to go...
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Old Dec 28, 2005 | 05:59 PM
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I've been running true duals the last few years without an H or X. I don't think they contribute to any noticable performance. However, I'm sure they will tone down the exhaust more than straight pipes.
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Old Dec 28, 2005 | 06:05 PM
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You don't need the H pipe, but a set of headers to that new exhaust system would help your 350. Hope your pipes are 2 1/2 in dia..?
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Old Dec 29, 2005 | 10:48 AM
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I have headers with 2 1/2 pipes straight back with no crossover... sound great and increased performance...
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Old Dec 29, 2005 | 10:27 PM
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I have headers and true duals through Flowmasters. Sounded fine, but then added the H pipe. Now lower rpms sound SOOOO much better, even if it doesn't make any more power.
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Old Dec 29, 2005 | 11:04 PM
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Originally Posted by 77BuffaloVet
I have headers with 2 1/2 pipes straight back with no crossover... sound great and increased performance...
this is what i have and its great. but i do have electric cut-outs installed fro somethin' extra!
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Old Jan 3, 2006 | 11:32 AM
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I just put on Dynomax ceramic headers with 2.5 inch exhaust back to Flowmaster 40's. A little loud for me but I can live with it. The part I'm not sure if I can live with is the resonance at about 40mph. BTW, I have a '74 L-48 with true duals.
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Old Jan 3, 2006 | 04:00 PM
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Duals with an H-pipe is good for nearly 10 horses according to all the motor-head books I have.
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Old Jan 3, 2006 | 04:46 PM
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I had Dynomax ceramic coated headers, true duals with H-pipe just behind tranny, going out to Flowmaster Deltaflow 50 series mufflers and loved the sound. I also had electric cutouts for that added noise when I wanted it. The 81 cats were less restrictive than the 79 cats, but if you add headers, I would recommend tuning the carb because you will probably start to run lean.
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Old Jan 3, 2006 | 05:46 PM
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you dont really need an H or an X pipe. If you like the way the exhaust sounds then leave it alone and move onto the carb and get the distributor recurved....
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