Just for grins I went out and put my Magnum 46 XLS on the test stand. Fuel = 15% Byron's, Air temp = 92F, prop = MA Scimitar 10X7.

Full peak = 15,100 rpm's and showing 285 degs F on infrared.
300 rich = 240F
500 rich = varied between 210 and 230.

I normally run it about 300 down from peak.

Like the others say though, temp doesn't tell you anything about your mixture. Too many variables; I just peak it then back it down about 3 or 400 and fly it like I stole it. [8D][8D]

P.S. These numbers are with a Tower muffler on it. It doesn't turn near that many R's with the stock muff on it and probably runs cooler too, although I haven't checked the temp with the stock muff.