Nice writeup zman.
Well i have argued this before on another forum. The s13 intercooler is not very good as it is qute small and its not very free flowing. But i think if your not after loads of power, want to make the engine a bit more efficient,keep it 'stock' looking and tidy it is a good modification. It is certainly better than not having an intercooler at all. It would be good for upto 200bhp i should think. (12-14psi on a t2 turbo with a modified exhaust and air filter)
its really upto you what you do. There are tons of intercoolers about on ebay and at the scrap yard. ones with a decent flow in and out for the gases and big cores are your best bet.