it's been discussed and it will not fit, if want a really fast celli and if you have the deep pockets and i mean deep pockets, your best way of an engine swap would be the 3sgte engine and go all wheel drive, someone correct me if i'm wrong though.
the 2jzgte(supra) will not fit unless you cut the car up and do some serious refab work.
the 3sgte will fit and would not cost as much as 10k if you get the 3sgte and tranny from the mr2.
if you get the motor and tranny from the gt4 it would cost you more cause the tranny would be useless.
useless because a 7th gen celica that is all wheel drive using the 3sgte is almost impossible unless you have serious technical/fabricating skills or your own shop.
one of the reasons why there is not an awd 7th gen celica with the 3sgte is because the tranny has a back housing that sticks out and it will not clear the fire wall of a 7th gen celica.(not even close!) the exhaust has to be rerouted,(for drive shaft)the gas tank has to be modified or moved (shaft and rear diff.)
a gt4 back suspension would be difficult to transplant onto a 7th gen celica.
the easiest way to get the back suspension would be to go solid axle and 4 link.
which will defeat the whole purpose of the celicas handling ability (straight line would improve but handling would suffer)
yes a 3gte can be transplanted into a celica but it has to be the front wheel drive transaxle mr2 version, not the gt4 tranny.
btw a cheaper way still would be to use the tranny of a 5th or 6th gen celica that has the 5sfe engine. it bolts right up and works except that the clutch disc has to be ordered separatly because the spine is bigger and the diameter of the disc is bigger of the 3sgte. the tranny has to be babied though.