Very interesting Sid. I didn't realize that the low RPM situation could be problematic... It just seems that since the goal is to lower IATs, that having it as a trigger would most ideal. Maybe some combo of factors, like an algorhythm of sorts. That sounds pretty wild though...

If all goes as planned, my MINI will be strictly a Fall/Winter (cool weather) ride in about a year or two. On a brisk day, I could be hammering it (high RPMs & boost) on some nice stretches of canyon road for several minutes before IATs go above let's say 60C or 140F. I'd like to find a way where I'm not draining the W/A mixture when I really don't need it, thus prolonging my canyon fun with this cooling agent...

I see what your saying though because if based strictly on IATs, if I need to slow down and even stop, IATs increment upward, and that could trigger the system to act, like at idle. I think this might be the ideal condition: boost or RPM (driver input/demand) above x or y AND IAT above z. Just thinking out loud Sid...

Heck, with the rear seats out, you might want to consider a tank there, or even a custom one in that concave area, and a simple cover or deck like lid over it. I just might do that as it makes use of the space, and shifts some of the weight a bit further back then the rear foot well area, albeit higher, but lower than now... Here's a visual: