tips dont change the tone, but they echo the sound farther which gives it a more metallic sound. The tip is all up to you. I personally prefer Magnaflow tips. I have 4" outlet tips 18" long, with 2.5" inlet. Looks amazing to me, have them side swept behind the rears. My tips were $55 each, $120 shipped.
Resonated tips help tone it down so to some it is, to the loud sounding guys no.
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2004 Ford F-150 XLT Supercab 5.4L 4x4
Appearance: Gloss Black Grills/valance/wiper cowl, 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.
Videos: Start Up, Revs, Driving. Fly-By Sounds Burn Out Video Interior Sound/Drone