Really, they've sorted the overcrowding... Ohhh thats why they leave people behind at Salford Crescent and Bolton every morning then...
And last I checked, between Hull and Leeds off peak a 2 car 170 is fine, just cut the calls at South Milford, Selby and Brough
Nothern's planners aren't blameless, "A 2 CAR 150 IS NOT SUFFICENT OFF PEAK!" theres so such thing as 'off peak' on the Bolton route, theres high peak and low peak into OR, off peak only happens into Victoria.
If EMUs wheren't in such short supply I'd be very contriversial and start cutting routes in half at Oxford Road to get more carriages running out North/West bound on DMUs, or combine DMU services up with the Buxton / Chester services then run Hazel Grove with an EMU again, basically, cut off the Preston and Southport diagrams from the Airport & Stockport and terminate at either OR or Piccadilly, if we're that desprate for EMUs then it would need to be done, but it's not just DMUs it's all rolling stock.