I spent hours and hours on exhaust and looked at every option out there. I looked at flowmaster, Magnaflow, Pypes, borla, SLP, MAC, etc. I spent even more time listening to each one and evaluating it. I personally was going for that nice classic sound (deep and throaty like a old Chris Craft) and just last month decided to pull the trigger on some GT MAC axle-backs. I haven't gotten them on the car yet, but they look fantastic as they sit. The 4in. tips are super sharp. I'm paring mine with a custom H-pipe over the X due to the fact the sound is deeper and less raspy. I will post some sound clips when I can, just waiting on the salt to clear in my area to get to the shop. Hopefully this helps and if you have any questions just let me know.
2003 Lamborghini Murcielago
2007 V6 Mustang (manual), Hurst/FR short throw, MAC dual exhaust, custom H-pipe, chin spoiler, GT front bumper, billet aluminum grill, GT500 rear bumper, GT500 wing, FR windshield banner, FR strut tower brace, LED interior lights, sequential taillights, FR side markers, slotted and drilled brakes, 93 Cobra teal painted (and cleared) stripes, etc.