a high flow cat x-pipe sounds good with flowmasters because it muffles the tinny sound, i would tend to agree with figment on the sound quality of an off road x-pipe on a mod motor with flowmasters, too obnoxious, i had 3 people in 1 week trade their x-pipes in and have h-pipes installed because they couldnt stand it anymore, as far as headers i would bother with shorties, the only shorty headers that actually pick up any power on a stockish type 4.6 are the BBK's, longtubes are good for power but like everyone said what a pain if u have clutch or tranny problems...etc...the bassani's are a nice choice for the midlength design although they arent cheap..if u give me a call at the shop tomorrow i can get you a price on teh bassanis, 727-571-1996

chad