The exact baud rate of transit is 4999600/12800 as the transit bus uses a nominal 4.9996MHz oscillator [1]. Having this correct can lead to quite substancial sync improvements.

Along with a PLL demodulator and symbol filtering the improvement can be quite significant:

Output of the old demodulator

The new flowgraph can be downloaded here.

References

[1] https://core.ac.uk/download/pdf/10339833.pdf page 8:

The exact operating frequency of the oscillator will, of course, vary slightly with circuit age and environment. The nominal value or design center is specified as 4,999,600.0 Hz, an offset of 80 parts per million below 5 MHz