Awesome info as always, FAQ Massa
From the UP FAQ:
What uppipe metal material is best? Uppipes are made from mild steel, stainless steel (304 & 321), and cast iron. There is no irrefutable evidence that one material is better than the other.
Now cast iron is positively the best? Is this just a theory or has it been well tested and proved? If it's the later then maybe we should update the UP FAQ. Same goes for the DP.