On the work truck, had the smaller dynomax super turbo muffler #17733. They were maybe a little loud, and had a drone at cruise rpm. Kinda got annoying after awhile, and the wife didn't like it at all.
Replaced the smaller turbo with dynomax larger super turbo muffler #17748. This muffler is longer, same height and width, and is noticably quieter at all rpm's. Plus the drone is gone. So a good deal all around.
The challenger did not have room under the rear seats for the larger turbo muffler, so I have installed the smaller ones under the seats, and along side the gas tank installed round Magnaflow #12616.
The interior volume of the small turbo muffler combined with the round magnaflow is greater than the large turbo muffler, but the round magnaflow is a straight thru style. So I"m guessing the noise level of the dual muffler setup might wash out about the same as the larger turbo mufflers, Kinda loud on the outside when your foots on it, but fairly quiet on the inside which would be fine with me.
On the Challenger, I have small block 360, feeding into hooker super comp headers with 3 inch diameter collectors. Continued the 3 inch diameter to a summit racing mandrel bent 3 inch X-pipe, with the X located under where the drive shaft meets the trany. Then used the X-piping bends to point parallel to the drive shaft, then reduced to 2 1/2 inch diameter which runs back all the way to the rear bumper.
From the X pipe, ran mostly straight back to the super turbos with TTI hangers supporting just aft of the muffler outlets. Then pieced together mandrel bent over the axle using 6 inch and 3 inch bend radii, then into the magnaflow mufflers, then down turns to clear the straight across rear valance panel. Used TTI rear hangers just forward of the valance, and appropriate metal straps bent to fit the hangers and welded to the down turns. The whole exhaust is mandrel bent and welded, except for the header to collector gasket, and clamped the over-the-axle to the outlet of the turbo mufflers. Did this so I could remove the rear magnaflow muffs with over axle pipe if needed to access the fuel sender, etc.
Need to get photobucket to post any pics.