im looking to do a quiet true dual exhaust with crossover on my 78 f250 4x4-460 stroked to 545 with blue thunder heads- wondering what headers and mufflers i can use that will be quiet yet still breathe well

 

Must ask why...but to each his own.

Take the headers of your choice.

As for mufflers, I'd suggest one of the "high performance" stock replacements. I'd also suggest around 3 inch pipe. That'll give a good sound, but won't be very loud.

 

holy (tire) smoke! a 545?
I guess you're looking to make a sleeper, eh?

Well, I did some research today, and found some pretty good info about all this:


Flowmaster makes a series of performance mufflers (no, I didn't have to research this)-- They are numbered 40, 50, 60 , 70

The traditional Flowmaster is the 40 series. It is the loudest and most aggressive sounding. It is the smallest of the Flowmasters, and has only two chambers. (It also gives alot of noise inside the vehicle) It also flows tremendously well.

The 70 series Big BLock II muffler is the largest, has three resonance chambers (which are both factors that help quiet an exhaust), and has their "Delta- Flow' technology-which is supposed to further reduce resonance inside the vehicle. I believe it also comes in a variety of inlet sizes and configurations- center/center, center/offset/, & offset/offset. (Offset/offset likely to be the quietest, as a center/center muffler is basically a straight-through design, and always the loudest))

Another tech point that I stumbled upon-
Exhaust gasses cool significantly- beginning immediately after they enter the first stretch of exhaust pipe after the manifold/header. (Particularly when the vehicle is moving)
So...the further rearward that the mufflers are mounted, the lower the amount of pressure entering the muffler (the exhaust gasses shrink as they cool- like the air in a tire). Since audio volume is pretty much a measure of sound pressure, you're mufflers should be most quiet if they are moved back as far as possible, taking advantage of the drop in pressure-- with no sacrifice in performance.

also, Walker (Dynomax) makes a series of quality OE replacement-style mufflers.
BUT-- I doubt that they are made to handle the volume of a 545, or even have the inlet sizes you want (2 1/2" to 3"), AND probably aren't any more subdued than a 70 series Flowmaster when not using the separate resonator which is spec'd for most OE exhaust systems.

Hope this helps

 

Exactly how quiet do you want this exhaust? If money is no object, I would look into some Magnaflow resonators, with some Magnaflow mufflers behind them, or any other brand combination (some Dynomax mufflers are pretty quiet) of the 2. My opinion of Flowmasters is they are junk.

For headers, pick whatever you can get that fits well, and has fairly large primary tubes. That much displacement with Im sure a cam to match will flow a lot of exhaust gasses, but Im sure you know that. Ceramic coating would be a good choice also.

 

The big MagnaFlows on my friends 502 HP 502 ci motor with X cross, 3" pipe is about as quiet as you can get a big motor without hurting performance. Besides that it's a good sounding system when he gets on it.
Check into SpinTech mufflers.
Vibrant has large oval extra quiet stainless steel resonators that have a perforated internal pipe not louvers that restrict as flow increases.

 

it doesnt have to be that quiet... i just want to be able to listen to the radio at interstate speeds (85 mph) or have a conversation without raising my voice

 

Spintech's go quiet above 2,100 rpm's, almost stock sounding at 60 mph. They will wake up when you get on it.
Problem I have even with the tailpipes out the rear is 14-1,700 drone as part of the tailpipe and tips are 4 1/2" diameter.