Sorry a bit late to chime in here....I removed my Dynomax Ultra Flo's about 2 years ago now. I had the Stainless steel versions for longevity under the car, but I kept getting comments about how hollow they sounded, and cackled from behind. Put a set of Flowmasters on and the car sounds much better, although I suspect they won't last anywhere near the 15 years I had out of the Dynomax's....which are still like new. 
