
Had an 08 ISF just catback and tune and now my 12 is catless headers/catback/tune. If I baby it at 50-70 28-29 is doable. 70-80 is closer to 25-27mpg. 80-90 is closer to 22-23 mpg. Fully stock I could still squeeze it to 27-28mpg at 50-70. A lot of flat land around me and I also have wider but lighter wheels, but the…