Is BHP the best indicator of how much fuel you need/how much gas your exhaust has to flow? If I wanted to run big boost midrange, would my standard injectors/3" downpipe/2.5" exhaust be a bottleneck? In other words, does 350 BHP at 4krpm have similar fuelling/exhaust flow requirements as 350BHP at 7K rpm?

It's a hypothetical question, I'm thinking, if I had to rebuild my engine, would there be any point in going the forged route if I was to stick with my current exhaust/injectors etc.