I have a 97 F53 460. The head of the rearmost exhaust manifold bolt was broken off when I bought it. It was somewhat noisy, sometimes more than others. From reading other posts I understand this is a very common problem with the 460 but usually just an annoyance, not a significant effect on performance unless other bolts break as well.
My solution, since the manifold had to be removed to replace the broken bolt anyway, was to replace the entire exhaust with a Banks PowerPack. Not cheap, but very effective if more power is your goal and quiet as well.
BTW, there were no gaskets under my manifolds when I removed them.
97 Aerbus XL3250, 06 Honda CH80
DIY Banks, track bar, acoustic insulation
Koni FSD front/Bilstein rear