PlasticMac
Admin Team
In the olden days, polishing manifolds was de rigeur, to achieve smooth air flow, (I spent hours of my youth on motor bike manifolds with Solvol Autosol). Nowadays, the theory is that the original cast finish promotes a boundary layer, that helps flow more than a polished surface.That is definitely sufficiently clean. I'm not sure what you are referring to when you say they are bent? They look to be the correct shape to me.
Either way your manifold is fine. The potential problem is build up of "crud" in the area that the flaps move through, that stop the full arc of flap movement
Mac.