ls1, intake, TB and catback, A4, went from 2:73's and no tune, swapped to 3:42's and a tune and now i get 15mpg with a very heavy foot and no highway, previously was in the 13mpg range with 2:73's and no tune
my old LT1 was in the 15mpg range with the 2:73's and a tune wen i didnt push it to hard