Dont do true duals unless that 4.0 is supercharged! Sounds terrible! I would personally do just one muffler and bring duals out of it. Thats just my personal experience with local rangers though.

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2003 Ford Ranger Edge 3.0L Vulcan Auto Tranny
MAC Performance Ram Air Intake
Flowmaster Super 44 w/ tailpipe before the wheel
Interior and Exterior LED w/ music interface
Ford Racing front and rear Sway Bars
Limited Slip with 4.10 gears

http://www.cardomain.com/ride/3114321