First off, I'm a newbie to the website and so far I think its great! Secondly, I also recently purchased a 98 5.0 AWD XLT two weeks ago. I have had several Rangers and a couple of Mustangs (all pre 87). Now to the main question. I went to the local muffler shop (Kinneys Muffler here in Hurst, TX) to inquire about duals. they recommended that i run a dual in/dual out Flowmaster with 2.25" pipes. They said that 2.25" was big enough even if I was to run 6 lbs of boost (If I was to install a blower in the future). To me this seems too small or will it kill low end power running anything bigger? What does everybody else think?