How so? I would perceive no difference between a turbo'd engine and a Naturally Aspirated one while driving on the highway at a constant speed. Engine responsiveness as per the parent poster would be the same within the city vs. on the highway.

There is no way to "solve" turbo lag.

I'd suggest researching variable vein turbos. BMW has done it very successfully in their e92 335s. Even resulting in a flat torque curve at very low RPM. It's impressive engineering.