My point more was that over the last 20 years we've been mainly focusing on changing combustion to reduce the amount of bad shit, like oxides of nitrogen, that are produced during combustion, which doesn't really add anything to the power produced by the engine as such.
I mean any workship can take a rb26 upto 4-500kw with the right boltons, but that doesn't mean nissan can (or could) due to the fact that it blows the emissions testing out of the window.
edit: at least that's my impression anyway. with regards to the motorcycle engines, guy next door's kid has one of the new ones, i think they're rebuilding it after less than a year of semi regular weekend only use...