The car I am speaking of was a 2001 Lincoln LS. Although it is an "older V8" the Blackwood software platform used in the ECU was very far ahead of its time. It was also shared at the time with its platform cousins the Ford Thundirbird and Jaguar S-Type. This software was actually used as the "prototype" software for the 2004+ Ford F-150 and 2005+ Ford Mustang. The major difference was that the 3.9 Liter V8 in the Lincoln LS, Ford Thunderbird, and Jaguar S-Type responds very well to induction and exhaust modifications.

Every engine is different. Although psyshack used one in a Honda Accord, there are many factors in place. The first factor is that when one performs a "performance modification" to their vehicle, it generates a tendency to want to utilize said performance modification resulting sometimes in a heavier foot. Other factors can include the ECU programming and its ability to compensate for the additional air intake. Most newer ECU's will compensate for a certain ratio of intake air to maintain the perfect 14:1 Air to fuel ratio. Once too much air is introduced, some older ECU's could not compensate in the proper way resulting in the fuel injection system over-compensating and causing the engine to run rich. This is where psyshack likely saw his issue. Although the heavy foot theory is the oine I am sticking to based on the "by the butt dyno" and "louder at WOT". This would indicate a more aggressive driving style that of course would result in a lower MPG. Now, I will admit if I am wrong and there is a certain level of assumption here so if I am 100% off base, I apologize.