ok heres my story to let you guys know im not a noob . and first post. (I searched also on holset, just didnt get the info i need)
my first time turboing a stock motor was the 5sfe in my celica.

blew the first junkyard turbo. and the second... wanted more power and a better powerband.
so bought a jdm 3sgte, put it in my celica. got it running turns out it had a blown headgasket. fixed that.

got it running Mint at 15psi then this.

fun stuff. so im sick of Fixing this thing and while the tranny is off the motor is half out i wanted to splurge on a new turbo.
ive read that the holset turbos are great on the DSM boards, but otheres say they arent supposed to see the temp that a gas engine sees since a deisel runs cooler.
saying that the turbos wont last long at all. well i was wondering what size holset i should look for my 3s at say 350 whp.
i know what i need to do for the supporting mods to get that high i just need a turbo large enough to flow some phat CFMs. something that flows around the same as a td06, or a gt30

heres a pic of the current car/motor.

 

HX35. You'll need a new manifold/downpipe, some larger injectors, engine managment. Same stuff you'll need for every other turbo upgrade.

Head over to Celicatech.com and read up in the forced induction section. I think some 6XXcc injectors and an SMT6, along with a new manifold/downpipe should get you there.