for my 400 in my elky it has stock manifolds but has a small leak and it was also not liking to turn over when it got hot. I picked up a heat shield from my local autozone in that section of "help" parts. If I recall it was under 5 and was just a piece of metal that covered the solenoid and left a small air gap around it for cooling. So far no troubles since but once I get my headers installed that could change
