My 98 355 has its third exhaust manifold on the passenger side and it is now leaking. My mechanic tells me he has replaced 10 to 15 RH exhaust manifolds and never a left side. He also says that Ferrari has not improved the manifold and just provides another one which will also fail in 15k or less. Tubi may have solved the problem but at $4500 it is an expensive fix. Fortunately the emissions warranty on a 98 is 8 years or 80k but if it keeps failing sooner or later you run out of warranty. I would like to know of others' experience with this.