Under hard acceleration, this is totally normal, but at an idle or at part throttle it's not normal at all and is usually caused by two things; 1) Either you are running real lean (not enough fuel), or 2) Your timing is too late (retarded).

Should my exhaust be glowing red?

The reason the muffler is glowing red is because the exhaust temperature is off the chart. This (highly likely) means that the ignition timing is out, or the fuel mixture is too lean.

Why is my manifold glowing red?

The exhaust manifold does get very hot but if it is glowing cherry red it could be a restriction in the exhaust/ restricted catalytic converter, it could be a lean air fuel mixture, or retarded ignition timing all of the above should cause a loss of power or fuel economy.