I've been thinking about the heat factor recently, especially as I'm cooking on electric and the heat is just not as intense as a decent gas burner. Three things I have done which have really helped get "that" taste:
1) added some jaggery sugar with the spices, as sugar helps to raise the temperature
2) added my ingredients in stages, so not to overload the pan and reduce the heat
3) once all gravy added, in stages, just let it blast on full and not been tempted to touch it until ready, I found it really caught on the bottom, but no burning at all, just a fantastic BIR taste.
Hope this helps others who are not lucky enough to be "cooking on gas" or a shopping trolley for that matter!