Considering having two of my 1958 Johnson 7.5hp’s converted from double pressure fuel line to a single fuel line w/fuel pump.  I remember reading where there was some discussion on the factory original covers with their curved inner wall performing better than some of the aftermarket flat surface bypass covers.  Is there any thoughts on this?  Seems if there is a difference in performance I would just remain with the factory double pressure line set-up .  Thanks, Shell in Oregon.