2000 is the crossover year, earlier ones had practically indestructible coilpacks (you can tell early engines as they have an old fashioned cable throttle - later ones are drive-by-wire) but the later ones seem to be made of chocolate.
I've heard of red dot, can't really comment on how good their maps are.. never driven one, but i'm always weary of tuners who claim to map every type of car.. which means they specialise in nowt.
Did he say why it needed a new turbo? It may be a bit of a lemon, but if you can get the car dirt cheap because it has running issues then find an easy fix you're onto a winner.