Well just from my own looking into turbo chargeing the tezz the info i got:
If you do turbo the tezza and want it done rights its alot of money and time, , Alot of small things need to be sorted its not a case of bolt on a turbo , Plug in an ECU and away you go. .
What you need to do is, Turbo, Front Mount, Injectors, ECU (and a person thats good at mapping cars) and then up rate the clutch, Metal head gasket and then mabey a stroker kit... All that provided you have an altezza engine thats running 100%
If you dont do the above, and just do the basic for the turbo, Really what your doing is helping the engine rip itsself apart and at high revs theres a BIG chance your engine will go pop or when your doing your diffing or what ever your into, , It could still go pop even after you have all the above done and uprated, Thats the joys of putting a Turbo on a non-turbo engine..
Theres a few Turbos on site, Like Nicks, Robin H, and Nenaghcorolla , , They all have turbo altezzas so drop them a PM and see what info they pass on and what they are like to live with, , I have spoke to all 3 and they will give you good advice.
My own advice would be save your money and buy a car with a turbo, Skyline,Sylvia,180. If you dont like cars like these and want to keep the Altezza, Stick a 1jz or something into it
If you go this route drop Squire on site a PM as he's doing this as we speak.
Hope the above helps