1. first off, what all can you port and polish? just throttlebody, upper/lower intake manifolds and engine heads?

2. if i buy a bbk 56mm throttlebody would it already be ported and polished? or would it be better to port and polish my stock throttlebody?

3. why don't auto manufacturers make their parts performancy from the factory? it doesn't seem like it would be that more expensive, for example, why not just have underdriven pulleys stock from the factory?

my car is a 98 v6 mustang.