don't even dare to change the bg!
that's the best bg change i've seen in a while
i like the kit, looks mugen like to me, which is good, though the area under the near triangular vent, the bumper looks kinda smudged
about the enterior, i'd sugest just to rebrush it as it is, make it blend, up the quality of it to the max, and maybe a mild roll cage, some small racing details will do the trick,
one last thing, the ref from the body on the front spliter doesn't look the best
keep up