M .78
Cost index assigned to international/regional/domestic routes are given by the company.
PR uses 27/26. 5J has it's own value. Zest has their own too.
If we would like everybody to fly the same speed, route, and flight time then I guess management of all those operating A320/A319 should have a sit-down so as to fly with no complications at all.
But I guess this would never happen...