you can do various swaps, depends on the car..
for example, you can swap in a v8 from an SC430 into your MKIII, a 7MGTE (since the car starts off as a 1G), or even a 2JZ, which is what I have done..
I believe there is a 1JZ, but I'm not a fan so I haven't researched further
depending on what engine you swapped in, you can swap to a single turbo, twin turbo, or if you're NA, individual throttle bodies and such.
you can also convert a FWD car to RWD like a Yaris, or AWD for the Supra..
there's all kinda of neat things to do...
here's my 89 replica..