After searching high and low through countless video clips, I went with Flowmaster AT Classics (part #817460) for my new '10 GT and left my factory H pipe in. I learned quickly that microphone location and quality of mics used produces severely inconsistent sound clips so I had to roll the dice. For this system, Flowmaster advertises a very deep, throaty sound going back to the 5.0 glory days....... and they hit it perfectly. The techs in my shop can't believe a simple bolt-on axle-back install could produce such a deep sound. Flowmaster must have gone back to the drawing board on this system to bring customers back to their product. The fit is spot on and muffler construction is vault-like so there isn't annoying resonance through the floorboards and such. In addition, they are ALWAYS deep no matter where you are in the rev range but