That is what I dont know...I know that when fully warm and at idle my streetbike exhaust gives temps (at highest temp) approx. 375 (while stopped) at the hottest point on the header. 1.5in down from the mounting bracket.....But that is a 4 stroke, 3 cylinder, 955cc injected bike.... And that is at idle, I do not know if it would increase or decrease with the RPM's raised. So I was basically wondering if anyone knew what the hottest temp (at any time) is on a 2-stroke 250.....