Sim Locked Viva~Flashing Question

[Diagrax]

See i have The Viva Sum unlocked and i was wondering if i hack/unlock the phone and flash a cooked rom will it still be Sim Unlocked...its a simple question so a yes or no will do but i do appreciate agood understandable answer...thanx in advance

[Diagrax]

The reason is because i bought a Viva unlocked and flashin a rom practically changes the whole device so i was wondering if it affected the Sim Unlock on the Device.( i have T-Mobile and had the TMo Wing(herald/Atlas))