It would be great to see the class 156/158 come to TSM also some tours like derby Nottingham London st Pancras and the Cornish mainlines, London Paddington to Penzance via Bristol temple meads etc
The 156 is already in this game https://store.steampowered.com/app/65217/Train_Simulator_Class_156_Loco_AddOn/ The 158 is already in this game and you can by routes which feature this train https://store.steampowered.com/app/...rcle_Line_Edinburgh__Dunfermline_Route_AddOn/ https://store.steampowered.com/app/258653/Train_Simulator_LiverpoolManchester_Route_AddOn/ Peter
There are many scenarios for those routes, although the class 156's don't run it and the FGW/GWR 158's were/are more local to Bristol, Cardiff, Taunton and Exeter I believe. Probably scenarios out there for those on JT Western Mainlines if you have a look around...