I cant make out anything bad about fitting a turbo to a micra. How much it costs maybe? Apart from that i think the average sized turbo is a t25. Ive used a t3 and am going to use a td04 which is a better sized turbo in my opinion. Good things are how fast they are, the looks on other people faces and the smile on your own, fuel consumption isnt all that different, you can run it on standard internals, its not that hard to do the conversion yourself.
Basically if your serious and got a constant flow of money go for it
BOOST BOOST BOOST!!!