I was wondering if someone would be willing to implement upgrades for the Mk.1 Mail stock to incorporate the 110mph rated stock as used on the WCML prior to the introduction of DVTs.*
At present I am constrained to operate mail trains on 160 km/h lines due to scheduling difficulties of working multiple top speeds together, and short of aviation, 160km/h seems to be the top speed as DVTs are replaced by post-privatisation MUs.
* in real life this was only on the Mk.1 mail/brakes and certain mail carriages, but not TPOs, though there wouldn't have been anything stopping the latter being uprated as well.
This is an interesting thought - did you want to have a go at adding these as upgrades? They would not need new graphics.