Got the word that up 1500 was possible, BUT, in most cases doesn't seem to work. Also that boost is problematic as well.
I think you're starting to see the different way to manipulate the speed control to make it work the way you want it to, which I believe will also help to get you back to better operating temps, with the added performance. Once again bertrands recommendation is very accurate, and he could probably give you better insight on how to manipulate the available settings to get what you want it to do.
As a note I was starting to think that without changing your settings but your fdr would be moving the acceleration rpm to different parts of the track which is why it would start to feel very different.
Hope some of this helps.