This can be caused by the exhaust valve being either bent, worn or not seating properly. If this is the case then get this checked out A.S.A.P as this could cause severe damage.
there is only one reason that i know of to make exhaust manifolds turn red
the timing on engine is to far advanced
have the engine timed .if the distributer is loose this will cause it
if...
Check to see if the engine is overheating, then check the exhaust system to see if it is clogged. If it is clogged, find out the reason why before just replacing exhaust components....