Quoted From hbvx:
^Maybe the lowering efforts previously somehow adversely effected the fuel economy relative to the aerodynamics? Great tips on tires and keeping them inflated, generally 1 PSI per 10 degrees, so I check my tires once a month or after drastic temperature changes.
Actually that might improve aerodynamics, think LeMans race cars.
That said I suspect you’re dealing with the ‘modifications’ of someone else and to be honest the only way to really know what’s happening in there is to take a look at the live data and fuel trims to see where things are, they may have installed a new ECU to run a different fuel map for performance purposes.