It has been done before, a couple of times. It would take a lot of effort and a lot of money!! Running gear etc... Depends on how much money you've got but GT4's are classed as family saloons so the insurance is pretty cheap, they're easy to mod (you can reach ~300BHP in an ST205 with little effort, takes a little more with a ST185) And they're cool cars. 200sx's make for a spirited drive, S14's are becoming really affordable now, S13's are great looking cars and cheap as chips these days too if you can find a good one.