Wotcha and welcome - as above there are quite a few differences which also run to chassis strength as well - brakes, suspension, anti roll bars, I think you are missing a rear one on the GX which is in place on the turbos, stand to be corrected on that one but there may well be a diameter difference if it is in place.
Buying a pranged donor car and effectively re-shelling it would be one way to go - that way you can see the specific differences between the turbo and non turbo motors.
I had a hatch STI and am now driving a hatch RX - they are poles apart in performance and handling with the latter being very soft across the board.
Any chance you could get a drive in a wrx or STI to see for yourself?