I bought a pair of old Edelbrock 5501 stainless mufflers at the local swap meet years ago. When I went on line to find info on these things, I couldn't find a thing. Apparently the 5501's aren't made any more. I wonder what they sound like, what they cost new etc etc. They have 2.25" inlets and outlets inline with each other in the middle of the muffler ends. Anybody got a clue? Plan is to put them on my 34 ford with Pontiac 370 motor.
My roadster has had a pair for 19 years. They keep things o.k. at low rpm and you know you have an engine as the rpm increases. They flow well as they basically flow straight through, with a divider in the middle.
About 20 years ago, I installed an Edelbrock cat back exhaust on a OT Chevy truck & was really pleased with it! IIRC
I installed a set on a customers car back when I had my custom header/chassis shop. If I remember right, it was a '35 Chevy coupe with a 409 in it. He got them free through a friend at Edelbrock. It sounded great. I remember thinking I would buy some for my own car when the time came. I usually used Hooker AeroChamber mufflers when asked for a recommendation, they sounded good on almost everything.
Is there a straight shot through the muffler? i.e. can you see directly through from inlet to outlet? If so, they are probably much like the Magnaflow mufflers, basically a twist on the glass pack idea with perforated tubes that allow higher frequencies to escape out of the exhaust stream, which are then captured in fiberglass packing in the surrounding housing. They should flow well, and have a deep tone, though they should be pretty loud.
The the flow goes in, is split apart and merges again before it leaves. You can see light through them, although not directly because of the separation part in the middle. No chambers. Kinda like the opposite of an X pipe.
I used them once on a 69 vette. Mounted them in the rear in place of the stock mufflers. Stainless steel is necessary as vette mufflers don't always get hot enough to burn off condensation and they are prone to rust. Sounded nice and the size was spot on.