With the 15/48 mine's starting to wind up pretty good. I added the XR400 cooler to mine. I'd guess about a 25 to 30 degree drop. I'll be curious to see what happens with mine when the temps get above 80 :) There is a person on the XR400 forum claiming that there isn't really enough air flow on the XR400 oil cooler where it's mounted. That all it's cooling is done by convection. He was also trying to validate that his new headlight configuration, that blocks air flow, wasn't going to make the bike run hotter. I do like your cooler setup though.
84 Honda Goldwing (GL1200)