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I looked at the same question before buying headers for my 55 and 56. I lean more to the old school look, but i do have 2 " drop spindels on both cars. So i did have some concern about clearance with full length headers knowing that i prefered the sound and added performance of a quality set of long tubes ( full length ) headers . Some people dont like to see any of the exhaust underneath their car, but as long as it is not hanging low and is tucked nice and neat with only the header collector partially showing thats the way i like it. Give me full length sound performance and looks, other than that i had just as soon not even have headers any other way. My 55 exhaust turned out great with no clearance issues either. Plus i added stainless electric cut outs which i am glad i did they are a lot of fun. I can go from mellow to full race tone or anything in between with a push of a button.
 

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The benefit is flow. But I would think, on most engines (other than high performance) you wouldn't notice the difference. You might find the convenience or huggers, the way to go.
There are long tube headers that don't drop low under the car.
Long primaries help to scavenge the exhaust from the engine. The idea is the shorter pipes are more likely to allow the exhaust pulse to stop or reverse, while inertia in a longer pipe helps evacuate the exhaust. Pipe diameter plays a big role in this at well.
 

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on a street car, with mufflers.

there is no benefit to long headers, over short headers.
I was a designer at Hooker headers, and we did alot of testing.
once you add exhaust and mufflers, the length of the headers becomes irrelevant. as far as efficiency and HP on street driven cars goes.
The scavenging takes place in the collector, so header length will not
be a big factor, longer headers will slow down the pulse, but when you add exhaust and mufflers you have created back pressure, which will effect all aspects of the exhaust, (scavenging, flow, efficiency)
block hugger headers do not have an efficient collector, so unless space is
an issue, I'd choose 3/4 length for fit and easy of installation.
 

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no, not hype

just not needed on a mufflered street car.
same with equal length, on a race only car, yes they are needed, ( usually high rpm)
on a street car, with full exh and mufflers. no gain in full length or equal length.
as soon as you connect the exh pipes to the collector, its acts like a very long collector, with back pressure.
so no gains will be seen with equal length, or long tube headers.
the collector assists in scavenging the exhaust from the primary tubes around it, it helps pull the exh from the other tubes.
imagine a 5 ft long collector, the exh pulses are not strong enough to carry that far, so after about 8-10 in , there would be no benefit, in that long of a collector, thus the industry uses a short collector (usually 5-6 in)
Now all that changes when you add on mufflers, as you have just created back pressure, and the exh pulse has resistance to flowing down its path.
it now reverberates, and sends a pulse back at the collector, confusing the exh pulse. disrupting the scavenging in the collector.
Than there is the H or X pipe..............
another time for that one,LOL
 
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