I think you would probably get the best results wrapping manifolds and up pipes.
I'm not familiar with the different kinds of wraps, but there are disadvantages which you may be aware of such as condensation buildup underneath the wrap if the exhaust doesn't get hot enough, which in turn causes accelerated corrosion.
If its affordable/feasible, I think the best bet is ceramic coating.
just my opinion. There are fortunately others who know lots more then me!