There are a few blown Holden and Fords getting around down here. As for emmissions, you will be fine so long as it complies with US standards and emmissions laws. You are going to have a few problems getting parts but that is pretty standard with anything Mustang. Getting it on a dyno for a tune could also prove tricky as not many people have the software to hook up to US cars.
There are many people down here with good knowledge so the added power of the blower will far out weigh any initial problems you may have. Besides, I hope to have mine blown next year

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1995 Mustang GT - Vert
RHD Conversion, Vortech V2-SQ, 42# injectors, CAPA Chip, 18" BonSpeed Wheels, 3.73 Motive Gears, AutoMeter Gauge Pod, Pedders Springs, Koni Shocks, 13" Cobra Brakes, BBK Shorty Headers
~~ He Who Dies With The Most Toys Wins. But Is Nonetheless Dead ! ~~