I was talking to a friend about target RPMs for given engines and got to thinking.

So every part of the engine is pretty much designed around a target RPM that it operates best at. For example, you would have a target RPM for an IVC for a given port knowing the intake velocity at that point.

When you design a motor for a broader RPM range, what kind of sacrafices do you make to achieve gains at given points vs others?

Would you design your exhaust to run best at a lower RPM or intake... or would you target them all at the same RPM and screw the rest?

I am not sure I am asking this the right way, but I dont want a simple answer like "area under the curve"... because that is obvious.

Are there certain components that have a broader range than others that are more responsive than others?

I am just trying to piece this all together, because it kinda sparked my curiosity (at 2AM). It almost seems like a flat TQ curve wouldnt be the best, because there would have to have been sacrafices made at some point to accomidate.

I know I might be asking for build secrets (or maybe not) that come from years of experience, but hell... its worth asking.