Tubular Manifolds generally crack because they are thin-walled when compared to cast manifolds. Coupled with the fact that they heat and cool frequently and the engine/exhaust pivot when the exhaust is red-hot.

We have had £1000 GReddy manifolds crack, so you aren't safe by spending more money.

I plan to have this manifold braced as far as is practically possible, if it goes ahead. It needs some really serious interest though, far more than so far.