Straight Pipes Bad? Yes
If you put Drag Pipes on, that is what U should be doing! Other wise you can waste your money putting Vance Hines Drag Pipes on and loose low end torque and will mess up your Gas Mileage. I did fix all of that when I purchased a 2004 HD Springer with those loud ass pipes on it. I bought baffels wrapped them in a heat blanket, or baffle material got 15-20 more miles to the gallon and great long hill pulling without shifting down it the mountains. And if you do your research you can damage your vales running straight pipes.