I have a 1991 Mr2 MK2, im about to put a 3sgte swap in it, i was wondering how i should run the lines to put an intercooler on it, i was thinking of taking some 2.5" metal tubing, filling it with sand, caping off the 2 ends with tape or something stronger, then i would crush the tubing, then run it under the car, would that be a possibility, or is that just stupid

Just buy an intercooler kit. i'll all bolt up in the side vent space.