How much difference do the cams and head porting really do?
 

With the new exhaust and intake manifolds? There's a few inexpensive first gen 6bts on eBay from buses, so they have the P7100 pump, and I really like the idea of dropping one into my K30 in lieu of the 6.2.

It looks like there's a billion different performance parts for these motors, all of which are supposed to help the turbo spool quicker. Would it be an exercise in futility to get a cam, ported head, and new manifolds in order to have a bigger turbo spool similarly to stock? Or is it mainly just a marketing ploy?

How does porting a stock head compare to the aftermarket cast/reworked units? Are the aluminum Fatt Tech cylinder heads still too new to have reviews?