I suspected that the proximity of the stainless bottle to the intercooler was increasing intake temperatures. Turn out that a few other owners have used this type of Volvo coolant header bottle, so I built some tubing & brackets to adapt to the stock location. The only thing I don't love about this bottle is the angle that the small upper return hose connects to. I made up a small metal tube with some 90 degree bends so that the return hose isn't at a funny angle. I might eventually cut the plastic pipe fitting off and epoxy a brass fitting in its place, but for now its working well enough.