Joust - If you have any pictures of your 2.5 engine with the factory power upgrade and overboost controller installed, I would be grateful if you could post them. I am trying to see if the top of the engine is/was the same as mine.
IIRC this upgrade was plug in all software jobbie. Don't think there's any obvious outside changes. It could only be done on the MBE ECU though. Some pics of the 2.5 in various states of repair here..