I have an '01 Sport Trac and I think the exhaust systems are the same as most other X's, cept my pipe used to swing to the side behind the rear tire, and most X's just go straight back. I went to 2 or 3 shops and wanted to get dual exhaust, but all of them said it couldnt be done, cuz its too hard to maneuver the second pipe over/under the axle or whatever onto the opposite side. So i ended up getting flowmaster 40 with a single pip, but branching to a dual chrome tip.... its pretty good, but at times kinda sounds like its "whining". so in addition to my response, i guess im wonderin if anyone knows why it might 'whine' like that when i step on the gas? i mean its a deep sound, but its kinda whiny, not like some of the good exhaust i've heard from like tahoes and stuff