cool exhaust manifolds

This is very good advice! I didn’t believe the hype with breaking a motor in with ceramic headers, now I’m a believer. I have Doug’s ceramic D450 headers ($$$) on the stroker. I did the break-in with them on the car, and now 1, 3, 5 tubes are discolored and kinda flat grey in color. For the cost of these headers, I wish I would have listened to people telling me this!!