Don't be afraid to get it hot. I've run my XPE for about 2 1/2 - 3 gallons now and it's a bullet. My engine usually temps in the 260 range (O.S. P4 Plug), sometimes hotter. I usually don't use a temp gun anyway. If it's smoking well, coming back to idle ok, and clearing out quick when you step on it... then it's right. No temp gun required.