We need to reduce services to a level that they can be operated punctually now, and compensate using longer trains where necessary. The 2-car DMU on the mainline needs to end.
Which services are you referring to? Pre-COVID the only 2 car operation in the Manchester area at peak times that I'm aware of related to services which did not have enough capacity or to services which were running away from Manchester in the morning peak and towards it in the evening peak. 15 years ago there were loads of 2 car trains in the Manchester area with empty seats. Since then passenger numbers have grown (a lot) and the number of seats per train has been reduced as accessibility improvements and bike racks have been added.
I also think most of the routes which can accommodate 6 carriage trains now have 6 carriage workings. If you're proposing platform lengthening and moving signals, then that's outside the context of this study as this study relates to what can be done with existing infrastructure.