I believe that the intercooler is as others suggest there to cool the air into the engine to boost power by allowing more fuel/air mixture to be burnt.
So not sure that a retro fit and more power would stop this problem.
was the engine known to run hot? if so make sure that the engine compartment ambient temp is correct, possibly fitting a fan to the engine compartment would help.
Volvo instructions state the amount of air flow required to the turbo on my engine and my surveyor sugested ducting air to the turbo area to keep it cool, in my case that is done as the air boxes are adjacent to the air intake filter.
I am sure if you find a solution Craig would be interested.
Charlie