Hello All, I recently bought my first new truck. 05 Cummins 6 speed LB in Silver. The best thing I've ever driven. Just a observation to all considering a change of muffler on the new 05 Cummins. After much consideration including the Aero-turbine I had my local shop install a 24" long 7" round Magnaflow and a really cool Big Dog 5" tip. I was looking for a change in tone, keeping the Cat for warranty issues and I got it big time. Way more aggressive sound especially when you stomp on it. I enjoy the sweet sound but if you like the new motor's quiet nature don't do it. I received many compliments from "diesel haters" on the stock 600's ultra-refined tone. That changed! I like it and you may, just be aware that it wakes up the motor considerably. Happy New Year! ;)