We are very familiar with the problem afflicting the F355 Headers. Actually, they get so hot inside the cladding that the primary pipes eventually melt. The photos show a typical set with the usual damage.
We do not manufacture new manifolds. We rebuild the original parts.
QuickSilver can supply Stainless Steel manifolds for your F355.
Regarding the design, we cannot improve the efficiency of Ferrari's design - just the materials and the manufacture.
We replace the original primary pipes with thicker (1.5mm instead of 1.2) material and we use a higher grade stainless alloy (type 304 instead of 409).
We reassemble the headers exactly as original so all the factory bungs for emissions testing, etc are present.
We usually reinstall the original cladding (using new stuffing) so they are 'invisibly mended'.
We have been making these for over 10 years now and have done over 400 Cars used everyday and for Racing - we have had No Failures.
*Price is per Manifold - if you require a pair please order 2 in the Quantity box.