In the end its about budget. You can get a newer lower mileage A4 for the price of an older more beat up S4, and the logic continues into the RS4. You CERTAINLY won't outrun an S4 with your A4, if the dollar-to-dollar tuning is done on both cars.
On the other hand, you CAN outrun the RS4 in a tuned S4 with dollar-to-dollar mods. The RS4 is pretty peaked out as it is... to get more power out of the NA V8 you need the hardware mods, and even then you're probably just moving the powerband around. Hard to beat forced induction in this category.
On the other hand, you CAN outrun the RS4 in a tuned S4 with dollar-to-dollar mods. The RS4 is pretty peaked out as it is... to get more power out of the NA V8 you need the hardware mods, and even then you're probably just moving the powerband around. Hard to beat forced induction in this category.