you could mount some lakes pipe exhaust as long as you made sure it was below the bottom door sill otherwise the driver would have to climb in through the windows.
great work on this build, a little side discussion regarding this style of suspension.
While the "underslung" was a viable automotive suspension variation there were some inherant issues with the design that may have contributed to it's extinction.
With the axles mounted atop the springs, all the vehicle load was placed on the spring/axle mounting bolts, stress (were hardened bolts in use back then?) and rust prevention would be big problems (IMHO). When the spring/axle mounts failed then the car frame would be laying on the ground and not going anywhere. The more popular design (which we all know and love) with the axles under the springs placed the vehicle load weight at the springs and spring to frame mounts and even if these failed the axle would still be under the frame and not have the frame on the ground.