I have two -6 AN hoses for my transmision cooling lines they run within 2" of the headers. I'm going to run both lines in a-12 fire sleeve UNLESS someone knows putting both of them in the same sleeve will affect the cooling effectiveness. It will only be where the lines are closest to the heat source, maybe 2'
Which material are you using ? I was looking at the high temp silicone type for my fuel line with same issue ... that said since the pressure side is out of the cooler I would separate just for my own sanity although I dont hink heat transfer would be a real problem
Don't buy the cheap Summit silver heat sleeve. I used it and it was next to a header (3-4" away) and the silver foil literally fell off after a couple hundred miles.