I thought I would be clever and use SS pipe the first time Not one of my better ideas. The original mixing elbow was still serviceable but pretty cruddy inside. I'm sure it could have been cleaned and reused but for around $100 I just replaced it and put the old one in the spares bin along with new black iron riser pipe. The engine is now 16 years old so replacement seems prudent to me. Cheap insurance in my book.