Well since your car is far older than you and probably needs other things than a rigged up intake I would stick with the factory air box for now. But if you must know, then all you have to do is search since this has been covered time and time again. Sorry but there are too many people out there trying to do performance mods on old and leaking engines where more power is to be regained by repairs and maintenance then making an intake that sucks hot air.
http://www.toyota-supra.info/forums/...-intake-q.html