good effort on the arch work, most impressive.
i've just put a wing on mine, if i get home in daylight hours i'll try and take a pic of the car, otherwise it will have to wait till the weekend.
maybe something like the nismo v2 spoiler would balance it.
not quite as big as something like the veilside V3 spoiler. but enough to balance the rear out. i think the ings low mounted carbon wing would do nicely, but they aren't cheap.