Little things first. Intake polished? What intake? Intake pipe? Manifold? Where in the manifold? Polishing is one thing, porting is another. What have you heard specifically?
Gaskets? Wrong engine. Wrong coolant too. Series 2 cars with the orange DexCool have gasket problems, but to be honest, if you're thinking about modding your car, you should still replace all your gaskets from the LIM up before starting.
As far as Exhaust Manifold cracks are concerned, I've heard a few 92-95 supercharged owners say they don't have them, but that'* usually because they simply couldn't see them. Here'* some examples from one of my cars. The other car (supercharged also, but unmodded) has cracks similar to this also, but not as bad:
The bit issue here is that you won't be able to see these cracks with the manifolds installed on the car. You HAVE to remove them to find them.