So if the sensor needs to be under 750°C (1382°F) I wonder if I can safely assume a 200° loss of exhaust temperature between my heads and the downpipe. I almost never get that hot, though, and EGT's stay around the 1500°F range at max. A 100°F loss isn't too hard to assume, especially since the exhaust housing itself will more then likely be even cooler. The max. ambient temperature that I expect to be around the sensor will be around 200-250°... there is wiring there, so I would say that is a fairly safe number to assume as a max.