I still have the 3" factory pipe on my truck, muffler and all, would replacing the muffler with a piece of 3" straight pipe be beneficial??, faster spool up??, better fuel mileage?? I like the send of them straight piped, I just dont want to spend any money on a 4" sytem right now. What does everyone think about the factory system just straight piped, my truck is stock, except for a K&N air filter and a 16cm exhaust housing from HTT, the pump was advanced and the fuel screw turned in by the prior owner. Anyone have their truck with the factory 3" and straight piped and what do you think about it??