3" true duals on a N/A 3v engine and stock size gears are going to kill the transmission and strain the engine down low. Don't do it. 2.5" at maximum. And X piped. Start the 2.5" after collectors, before the cats.
Here is how hi-flow cats, 2.5" true duals X piped with Dynomax Bullets and 4"x18" 45'd tips sounds.
http://www.youtube.com/watch?v=Vi-L12mt5E4
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Appearance: Painted Headlamps/Fog lamps, 20% Tint, LED Reverse & Plate Lights
Performance: 2.5" True Duals X piped, Rear Cats Deleted, Magnaflow 11" Bodies, Magnaflow 4x18 Rolled Tips.
Suspension: Bilstein 5100 Leveling Struts & Rear Shocks. 20"x9" KMC XD Monsters, 33x12.5 Toyo M/Ts 
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