4-cylinder engine? My wife has an '06 4-cylinder Tribute and it is very annoing to drive on the highway because it is so underpowered and has to downshift to climb the slighest hill. I was wondering if there are any power add-ons such as supercharger, turbo, cold-air intake or other that are available for the tribute. Would add-ons from the Mazda3/6 or Ford Focus with the same 2.3 engine work on a Tribute (i.e. would they fit in the engine compartment)?