Odd question, economy enhancing mods
This may sound strange, but you often hear that one of the fringe benefits of certain mods designed for performance is that they have a positive effect on fuel economy. i.e. an exhaust helps the engine breath easier = less resistence in the engine.
So from experience here, what mods have had the most positive effect on economy and (i know you probably never meassured this) but by how much.
Just might help me sell the idea of mods o my girlfriend if they save me money in the long run.