I had the American Thunder Kit on my 06GT but my old ears and nerves got tired of them. I removed them and have them in storage and put my OEM mufflers back on with my headers and off road X-pipe and it sounds great to me. The American Thunder set has the original 40 series mufflers, I think, and the chrome 4" tips. I'd let them go fairly reasonably, I think about $200.00 plus shipping. I'll post some pictures as soon as I get a camera.I don't know what to get i heard the new 44's are good but do i want to go with the original 40's, some please help with some tech.