I'm repairing the body shell of my '70 Barracuda and adding stiffeners where necessary, which seems a good time to plan for headers and big pipes. Don't want front inner fender bracing to get in the way, and need room underneath for 3" pipes.

I haven't seen many photos of headers on e-bodies. Search does show Doug Thorley headers are the top pick.

Love to replicate the header 'ping-pingping-ping' idle sound from a solid roller cam.

Are headers no making much difference? Too much warping and exhaust leaks? Not enough room?

I run ceramic coated TTI's on a '70 Challenger. 1 7/8" > 3" collectors and pipes on an Ed head low deck. They fit exactly as advertised. Once I ditched the gaskets and ran high temp RTV only, no leaks in 12+ years. Also no underhood heat issues including long hot weather drives and road track duty.

Running 2 inch TTI's with 3 inch exhaust on 70 Challenger, Fit well, tight at stock PS box,,,had to move engine slightly toward passenger side for clearance. Switched to Borgeson box,,,not only for clearance,,,much more room.

Biggest complaint,,,,nice chrome look ceramic coating eventually dulls to gray and sound as leaking, when not. Stock manifolds are much superior in that regard.

Spark plug access though doable is tight at numbers 2, 4, 6 cylinders. Number 6 the toughest. No way to get a compression gauge on any of them that I have found. Have tried a variety of screw ins and plug ins.

Certain cars don't gain much from headers. I wasn't sure if that was the case with Chrysler BB motors. I can't feel any gain under 10%, and the gains I see are may 20-30hp.

That being said, I'll rebuild the 383 as a stroker and put heads and cam on it with a 500hp goal. Deep breathing engines should benefit more from headers.

I did find a blog on header brands on Moparts: http://www.moparts.org/Tech/Archive/exhaust/17.html

You WILL be far better off with headers on it.. MOST of
the manifolds are a choke point except a couple of
manifolds and they tend to be the race type

Mopar big blocks LOOOOOOVE long tube headers. Absolutely, without a shred ov question worth any hassles. Just get GOOD ones. (changing plugs on my cheapass Hooker comps w 440? NOT worth the hassle)

You get what you pay for. Do not buy an outdated design. Dougs. TTi's.

One thing though... what you DONT want... IS that ping-ping sound. That is the sound ov garbage headers. Thin tubes, crappy thin flanges, maybe even poorer steel? Thats the sound ov compromise. Listen to a car with GOOD headers. ALL you hear is the exhaust... coming out the loud end. Thats how it should be. I just shake my head when a guy revs up a big dollar build and i can hear the exhaust right near the engine... Or when the engine compartment is louder than the rear...

Performance will depend on the engine, actual use of the car and how well the header design works with the rest of the package.
For example:
Too large on primary pipes off the head and there will be little gain at low and mid range (street use).
For more on this, search for Calvin Elston's posts on Speedtalk, and/or run your specs through Pipemax.
Cheated turns will hurt velocity and potential performance.
see http://speedtalk.com/forum/viewtopic.php?f=1&t=36849&p=449613

Pipes that get in your way or put heat into the locations that are not so tolerant of heat are drawbacks of a different nature. That said, there are some creative designs you can look into including Shorties (TTI, maybe Sanderson) and Tri-Y (Schumacher).

Another consideration is flange sealing. Few mass produced headers have trully flat flanges. Some try to solve the issue with a raided bead around the ports. These require a soft gasket.
see http://speedtalk.com/forum/viewtopic.php?f=1&t=48643&p=643888#p643888