i think you would be referring to the ep82 starlet gt from japan...
i had 1 of those engines in the latest model ep91 starlet..
common upgrade path?
well the gt starlet gave you the option to run high or low boost
low would be something like 6psi?
and i always use to run mine on high boost 9psi
and 10psi on a cold night..
but as for an upgrade.. i would 1st do a full exhaust..
then probably and front mounted intercooler..
and heavy duty clutch with lsd gearbox
i had heavy duty custom clutch and the lsd gearbox and that really was great !!
as for the turbo upgrade
i wouldnt upgrade the ct9
it does the job at 9psi
as for the suspension upgrade
it is DEFINETLY NEEDED !!
i had the gt starlet strut brace and full suspension setup on my ep91
and it still felt crap
so thats the 1st thing i would do is upgrade the shocks .. springs are not to bad but the shocks are hopeless..
mid 13 second?
alot of mods
as for problems?
not many i guess ..
but the problem i had was my spark plugs lead had a crack in it and was shorting on my topmount intercooler...
so just make sure when you buy the motor or car check the wires because i dont think toyota australia stock them they have to be ordered from japan...
aftermarket computer?
i think a couple of people on the starlet forum use the e manage by greedy
not all of the starlet gt's come with standard lsd's ( i could be wrong )
ofcourse there is always better aftermarket lsd's out there
problem is finding them and the cost of them..