Hey guys,
Some questions I hope you want to help with:
How did you tackle the by the ECU expected separation with the dual pre-kat O2 sensors in your equal length 5-1 manifolds?
What is the runner length you tried to achieve and (if applicable) based on what calculation?
I guess you understand where I’m going to… 
My OEM manifolds are getting tired; flexy bits are dying, nuts and studs rusted so once the workshop is done, first thing is engine out to fix some leaks GregB style and start cutting up some stainless mandrel bends!