ian, keep in mind if u purchase a set of turbo's from nengun, ur likely to get hit with import tax, and that will soon blow the price of the turbo's way up.
going a single would be too much hassle and money. you need new manifold, dump pipe, front pipe, intercooler piping, afm piping, water & oil lines. and then it'd be majorly defectable, caus it'd be the first thing the coppers see when they lift ur bonnet.