When I wrote Bang for the Buck I was going from the perspective of a person who has a stock FI car now (which is what you guys used as a baseline).
If that person had a budget of say $1,200 to $1,600 for performance mods, and wanted to get the most bang for their buck, would that person get more HP and torque by putting their budget into (for example) Matt's head and cam, or this header and exhaust system?
We do know that from baseline the header and exhaust gets us about 7 more HPs and Ft-Lbs. I got my $1,100 number from looking at my specific circumstances that require the use of the stock cat for meeting emission inspection regs. I assume the system is designed so that the factory cat bolts in and out.
We don't know from baseline what Matt's head and cam would give us. If there are any published figures, I would like to see them. I figured that IF Matt's head and cam could give about 9 HPs and/or Ft-Lbs more from baseline, that it would be equivalent on a bang-for-the-buck basis to the header and exhaust system. IF Matt's head and cam would yield more than 10 HPs and/or Ft-Lbs it would be a better value.
What would really be Da Bomb is to dyno test this header and exhaust system together with Matt's head and cam all installed on an FI car (since an FI car was used for the baseline).
I would think that the person interested in that combo would be someone who wanted to extract the most power from their car while staying inside the factory "sandbox"----without the extreme measures of an engine swap, and maintaining the use of the stock FI system (or at least the outward appearance) and stock exhaust routing and hangers so as to preclude any alterations of the chassis.