I've recently returned to NTP after a few months, I'd forgotten how good it is. The engine noise of the 45 is absolutely awesome, with all the gurgles, bubbles, pops and growls as you throttle and brake. I used to commute along the Trans Pennine route in the 80s/90s and I can confirm that Dovetail have absolutely nailed the sounds of these trains. Not just the engine noises but the track noises and everything else. I can almost smell these old trains when playing this route, great fun. Excellent job Dovetail. Full disclosure in the current climate of saying anything nice about Dovetail Games - I do not and have never worked, or know anyone who works for Dovetail or any of its subsidiaries.
Admiteddly, I haven't played all of the routes, but NTP is my favourite. It also de-throned my previous favourite, WSR.