That's quite a difference between the two: I like the yellow car much better. It has a crisp sound to it, whereas the GTX sounds like a 318 car.
Maybe '66-'67 cars are different from '68-'70, but IIRC the later 440 cars had an H and larger pipe before the mufflers.
Plus, the manifolds on the RBs should be further apart due to deck height, no ?

FWIW, my yellow car sounds pretty much like your yellow car - and it isn't because of paint - but my blue car sounds pretty much like the GTX.

Do the 6" round ultra flow sound or perform different than the more conventional oval shaped ultra flows? They might fit on each side of an ebody gas tank.

Found a pic of what I am considering.

Here's the chart for the Super Turbos. All of the single in/out Super Turbos will flow in either direction, but for an A-Body or B-Body you will enter next to the driveshaft on the offset, & come out for the tailpipe center.

Here's a pair of my chambered mufflers on a 68 B-Fish w/340: https://youtu.be/PdW5Vy1Dtv4 (I think it's one of our Moparts members' cars)

Both cars are equipped with a full 2.5inch TTI system , both are H pipe equipped
The 440 GTX is box stock.
the 383 Satellite had a small cam, approx 10-1 comp. and stealth aluminum heads

Here's the chart for the Super Turbos. All of the single in/out Super Turbos will flow in either direction, but for an A-Body or B-Body you will enter next to the driveshaft on the offset, & come out for the tailpipe center.

Here's a pair of my chambered mufflers on a 68 B-Fish w/340: https://youtu.be/PdW5Vy1Dtv4 (I think it's one of our Moparts members' cars)

Super Turbo with a center exit. The exhaust has to flow around the exit pipe. Not my picture. This topic has come up before and I saved the picture.

I'm looking at this picture and I can't fathom how this is not a pretty restrictive design with that exit pipe blocking the flow. The next set of mufflers I get will be the ultra flows.

I've used a race bullet as a resonator on a 4" system on my 2v valve Cummins ram , doesn't really do a lot to quiet it down.

Well, I used to work for Dynomax & I can assure you, a 2.5" version of the Super Turbo flows better than a 2.5" or 3" 2 chamber, 3 chamber, or Delta flow Flowmaster. The 3" Flowmaster versions had flow rates of around 350 scfm, while the 2.5" Dynomax Super Turbos have flow rates of around 410-420 scfm. Comparative OE mufflers have flow rates of usually under 200 scfm. I remember buying a pair of 16" bodied Chrysler "Hemi" mufflers from Mitchell Motors back in the early 80's - to replace the 20" bodied originals on my old '71 Hemi Charger. The mufflers from Mitchell flowed like CRAP - I could immediately tell they were restrictive. Back then I didn't know crap about exhaust. I should have installed a set of Walker Red Line Z mufflers, which evolved into the Super Turbos.

The big differences internally between a Dynomax Super Turbo & an OE muffler are two things: the size of the internal perf tubes, & the Super Turbos have flow directors (bank turns) at each end, & OE's do not, and most other performance mufflers won't either. If you buy a 2.5" in/out Super Turbo, it will have 2.5" flow tubes inside. An OE type muffler with 2.5" inlet/outlet, will usually have 2" dia internals. A CHEAP, crappy turbo muffler (like the Thrush California Boss Turbos) have 2 flow tubes internally & NO packing, plus the flow tubes are smaller diameter. Super Turbos have a fiberglass mat that wraps around the center section of the muffler (you can see it in the photo someone posted), but this mat breaks down in about a year or two, & the mufflers will get louder - especially the 14" ones. Some oval mufflers have two flow tubes, some have 3. The Super Turbos are GOOD turbo mufflers. The Dynomax Ultra-Flow mufflers are straight-through, & they do not "tune" the sound like Super Turbos do, so they sound different than each other. From a flow standpoint, the scfm of a 2.5" 14/20" Super Turbo offset/center is around 410, and a straight-through Ultra Flow is around 1100. There is a HUGE difference in flow, but do you really need the extra flow of the Ultra Flow? Only a few dyno runs could tell you. Bob Karakashian & many of the other guys running in the Pure Stock Drags are using the Dynomax Ultra Flows. Those WAAAAAY outflow flowmasters & all other non straight-through oval mufflers. The stainless Ultra Flows with the stock-style spun-locked heads, flow the same as the Dynomax race series welded construction mufflers - also now called Ultra Flows. The welded series are offered in bigger flowpath & bigger in/out than the stainless ones, so there is more variety. On a closing note, I don't know what the internals are like in the Accurate mufflers, & I don't know who is building them for them - I doubt they have the equipment to build them & especially fab the spun-locked heads. If they do, then that's impressive.

There are quite a few mufflers currently in the Dynomax & Thrush line that I suggested & partially designed. There were also ones that I tried to get them to bring to market, but was unsuccessful. One was reverse flow Super Turbos in 2.25" & 2.5" versions for AAR's & T/A's - the standard oval size but 20" long. *They currently offer these reverse flow mufflers, but they are only 14" long bodies - not long enough. Those were referred to as "fabricator" mufflers. I have been building my own chambered exhaust mufflers & mufflers for AC Cobras since 2002.

Bill,
I have the mufflers you are asking about on my 68 Hemi Road Runner. The 2.5" in/out Dynomax's. You are welcome to come up to the Phoenix area and we can go for a ride if you want??
Chris

Bill,
I have the mufflers you are asking about on my 68 Hemi Road Runner. The 2.5" in/out Dynomax's. You are welcome to come up to the Phoenix area and we can go for a ride if you want??
Chris

Chris the 2.5 in out is the 17748 , Bill was asking about the 17747 with is 2.5 in , 2,.25 out.