WAP-4 from any shed all over india won't matter. as long as the train is running. it was just an observation that i brought out. Duronto doesn't need WAP-7 as it doesn't need acceleration.. due to low stoppages. so it can keep running at a constant speed and wap-4 does wonders to it. yeah the trains which has more stoppages , specially the day trains and sf trains with more stoppages certainly need WAP-7 as it needs a better acceleration.obvious examples i quote- 'SHAN-E-PUNJAB EXPRESS, TAJ EXPRESS, HIMALAYAN QUEEN EXPRESS, BRINDAVAN EXPRESS, LALBAGH EXPRESS' to name a few of them