So I'm running stock 2.25" pipe from the Y to a 2.5" Super 40 FM and dumped after the axle. The Flowmaster muffler is showing signs of leaking water out the bottom and it needs to be replaced. I would like to know if running a 2.5" pipe from the Y to a 2.5" (new muffler) should cause less low end torque and decrease in gas mileage? I mean is there that much of a difference between running a 2.25" to 2.5" piping on a 1GRFE motor.
Thanks for any response or support,