heres some info, shoot me if im wrong
mivec bumper and proton bumper is the same, wont affect headlites.
using mivec bumper with proton fender gota cut at the side part, if dun one to cut confirm gota change mivec fender and mivec signal lites, because mivec signals is short and proton signals is long. 2 different thing there. as for the headlites, no matter u change hood, bumper, fender or watever, it stills remain the same, still can use proton headlites. as for the hood side, if change to mivec hood, need to readjst the bracket (the one tht holds the hood) because proton hood, bracket is higher than mivec ones, dats why u can see mivec hood dun need grill where proton needs it to cover the middle hole.
masdival: for ur qestion yes u can use back ur grill if ur hood remain proton.