the leaning out you may see on a fuel map is due to the millions of dollars in honda research. the air:fuel ratio is actually on the rich side for safety but every car and environment is different.
if youre talking about the drop in power after 6500rpm, thats more a result of the entire engine package rather than an inadequate fuel rail. not to mention the fuel cut. the cams, compression, head flow, etc. dictate where the power band starts to fall off…
so no, an upgraded fuel system won’t give you more power, but proper tuning of the fuel will. (regulator or direct ecu adjustments). when you reach the limits of these components, then you can start thinking of bigger injectors and/or fuel pump. the fuel rail will come much, much later.
